Challenge Run Guide

This guide will explain the scoring system and provide tips on how to improve your score.

Introduction

If you can finish a normal 20XX run easily and you want to move on and take part in challenges, this guide is for you. I will explain how the scoring system works and pass on some tips for optimal scoring so you can stop being jelly:
I will, for the most part, discuss regular/softcore challenges (Daily/Weekly Challenges) and at the end give specific tips for hardcore challenges. The guide is up-to-date as of patch v1.01.00.

Update Log

Updates I made to the guide.

[v1.00] 10/21/2017
– Published the guide.

[v.1.01] 10/22/2017 (Day one patch)
– Fixing typos.
– Added Forgotten Memento to the augs section. Kind of ironic.
– Added tooltips for images. You can now hover over item pictures to display their names.

[v.1.02] 11/19/2017
– Added Vera's DPS to the Power chart.
– Added section about beating Flat in less than five phases.
– Added another tip for Toxin involving Defiant Decree.

[v.1.02.1] 12/06/2018
– Not much of an update, I just lowered Oxjack's Ken in the helmet ranking because of the Boltdash/Dashbolt swap.

Scoring System

Your score consists of the following things:

• Enemy kill bonus: 1 point per 10 HP of a killed enemy or crate/chest (rounded up), e.g. if you kill an enemy with 110 HP, you will receive 11 points. You can find more information on this in the section Enemy Score Table below.
  
• Time bonus: 1 point per second left on the bonus timer at the end of a level (stops upon killing the boss).
  
• Stage bonus: 50 points times the current level number (1–10) when completing a level (received upon killing the boss).
  
• Efficiency bonus: 50 points times the current level number (1–10), minus 10 points for every damage you took during that level (received upon killing the boss), so 2-damage hits will reduce the efficiency bonus by 20. However, using red vending machines (HP -> nuts) will not reduce your efficiency bonus. This is basically a punishment for taking damage.
  
• Glory Zone bonus: 10 points times the current level number (1–10) for a completed Glory Zone. For example, if you beat a Glory Zone in level 5, you will receive 50 points. However, enemies you kill in Glory Zones don't award points, so if you fail it, it was a waste of time.

In the following sections I will give you tips based on my own experience in 101 Daily Challenges, 257 Daily Hardcore Challenges, 34 Weekly Challenges and 41 Weekly Hardcore Challenges (as of the time of writing this guide). A lot of the stuff I'm going to write will come across as super subjective, but most of the tips are actually consistent with the best practices compiled by the 20XX hive-mind community in novel-length discussions in the Steam forums and the Discord channel. I usually end up in the top 3 of every challenge run I play (to be fair, not many top-tier players play the challenges regularly), so all my advice is tried and tested.

Input Lag Reduction

V-sync

Let's get this out of the way first. Your game could have some input lag and you might not even know it. I used to play my first 600 hours with an input lag without noticing, I simply assumed this is the way the game is. But reducing the input lag might propel you into another league. For example, wall-jumping reliably onto and off of wind platforms in Skytemple used to be almost impossible for me, now it's a piece of cake.

So try this: In the in-game Settings, set the display mode to "Fullscreen (no V-sync)" and see if that changes anything for you. Try tapping left and right and see how fast your character reacts compared to the mode you were playing the game in before, or jump around the HQ a little bit. If you don't notice a difference, well then you didn't have any input lag in the first place, which is good. If you notice that your character reacts faster, then you should already see an improvement to your score from here on out.

Monitor

If you can and are willing to, play the game on a PC monitor, not a flatscreen TV. Even though my TV has a video setting called "Game Mode", there's still a noticeable delay compared to the PC monitor, so I always play challenges on the latter. I know not being able to play on your couch blows, but you want to raise your score as much as possible. If you are convinced that your HDTV is top-notch and has no noticeable input lag, consider this section irrelevant.

General Gameplay Tips

• There is usually no reason not to dash. This is not classic Megaman with wall jumps, so I want you to move through the levels in dash state most of the time. Play speedily, but don't rush so much that you end up taking damage – every time you take damage you lose 10 points of efficiency bonus, which equals 10 seconds that you could have rushed less. Stretch out your ground dash and then dash-jump, this is the most time-efficient way to move through the level. Holding dash and constantly doing dash-jumps is also OK. The only time you might not want to dash is if you need to make precise jumps while you're already overloaded with speed items.
  
  
• When you're not attacking, you should be charging. Doesn't matter where your thumb is resting on the controller, right? Might as well be on the attack button. This obviously doesn't apply when you have the Plasma Blender/Axe/Uncharging Force.
  
  
• If you're like me, you never liked using powers in any of the Megaman X games, and you may not like using powers in 20XX either. However, if you're playing challenge runs, powers are essential for a top score. Not only do powers scale much better than main weapons and often kill bosses much quicker, they also have tons of secondary uses that will save you a lot of time/damage. There is a section on powers below.

How to Advance through Unknown Territory

That's just a fancy way of saying how to play the Daily Challenges. Unless you're using a second account or watched some streamer play it, you will not know what the levels in the Daily Challenge look like and it's going to be like playing any normal, procedurally-generated run. So here's what you should do to maximize your score (in a nutshell, do everything):

• Always enter Glory Zones: They usually give more points than the seconds it takes you to finish them. The exception are Glory Zones in the first or maybe even in the second stage, but you don't want to miss out on a possibly good core aug, so enter these too.
  
  
• It's best to follow all bonus paths: Bonus paths are paths that branch off from your main route and end in a bonus chest, a store or a Very Safe Lab. 20XX doesn't have that many level segments, so after a while you will be able to easily distinguish bonus paths from the main route. You might get a pretty useless item at times, but most of them will be helpful, so skipping sidepaths will hurt your character build in the long run. The only sidepaths I sometimes skip are those really long ones in late-game Skytemple that take forever, and I only do it when my character is already overpowered and I don't feel like I need any more items – but even that is a risk, so it's up to you.
  
  
• Try to kill all enemies: Most enemies will give you more points than it takes seconds to kill them. Only consider skipping enemies if they are hard to reach and give very few points (Flapps, Alpha bees/spiders), or you feel like you're most likely going to get hit by them. However, every enemy could drop something useful. I usually don't go out of my way to kill individual stray Flapps, but they could drop a token which gives you the most amazing aug at the next slot machine, so it's up to you whether you want to take the risk of skipping them. However, as a guideline, kill as many enemies as you can. Especially soul enemies (the glowing ones), they give tons of points.
  
  
• After killing a boss, walk ahead and take a look at which boss comes next before you pick up the boss power or any of the two augs. Having this information might make you reconsider what to choose. It will make your total run time a few seconds longer, but not hurt your score in any way because the bonus timer has already stopped.

Characters

So, which character should you take for challenge runs? Which character is better suited and scores higher? That is a good question, and I cannot answer it. Sometimes Nina will have an easier time thanks to her safer long-distance attacks, sometimes it is Ace who can cut through bosses much faster with a strong main weapon.

That is why you should just pick the character you like playing with more and only compare your score to others who used the same character (there should be a character filter in the leaderboard, really).
However, most of the time Ace gets higher scores.

Nina

Use her long-range attacks to your advantage and avoid damage as much as possible. A good Daily Challenge with Nina means you get hit 10 times or less, 5 times or less in a Weekly Challenge. As for hardcore challenges, each run is different and damage expectations are kind of open-ended, so I cannot really give a reference number for those.

However, Nina's other advantage is non-limited DPS at point blank. Do you like mashing buttons? Yeah, me neither, but that is what you signed up for. The better Nina players save NRG by jumping in front of tanky enemies and mistreat their attack button instead of using powers.

When fighting bosses, Nina needs to rely on powers much more than Ace. While Nina's DPS is unlimited when fighting stage enemies, bosses have invincibility frames, therefore Nina's main weapons can take forever to down a boss. As a rule of thumb, take all powers that the bosses ahead of you are weak to (except for Shadespur). Also keep at least one heavy-hitting power in case you don't have a boss's weakness. More on that in the section on powers below.

Ace

Ace, a poet, video game addict and the guy who cuts the pizzas into small pieces before they get shipped for delivery. His advantages lie in better vertical range, higher boss DPS and better crowd control in stages. Often you will be able to move through stages faster with Ace than with Nina.

Ace's close-combat style comes at a slightly increased risk. In my opinion, losing 20 HP or less in a Daily Challenge is a good number, Weekly Challenges should be 10 HP or less. So if you're the type of player who uses Ace to charge at bosses and hopes they die before you run out of health, change your play style right now! You need to learn all stage enemies' and bosses' patterns and dodge properly if you want to get a good score with Ace.

Ace needs to rely slightly less on powers against bosses. His main attacks are generally pretty decent against them. However, unless you have the Plasma Blender or a strong ATK build, you should still use boss weaknesses, so take the respective power if the boss that is weak to it is still ahead of you (unless it is Shadespur, duh). If you don't have the boss's weakness, your main weapons will do fine in most cases, but you can use another heavy-hitting power if your PWR level is decent and you have sufficient NRG.

Main Weapons (Nina)

Avoid these:

I mentioned that Nina's strengths are unlimited DPS and long-range attacks. So don't do anything silly like taking Scatterblast (the shotgun weapon), thus removing both of Nina's advantages, long-range attacks and unlimited DPS. Scatterblast is quite useless in stages and only marginally useful against bosses (it's much better to rely on powers). Seriously, don't take Scatterblast unless you have an extraordinarily high ATK value and feel like you know what you're doing.

Wave Beam has recently been nerfed and it is now actually possible to miss enemies due to the increased waviness of its projectiles. In fact, the constant repositioning you will have to do with this weapon will cost you many precious seconds, so I cannot recommend this weapon for challenge runs anymore. It also lost its previous damage multiplier of 1.2 at some point and now does the same damage as the good old N-Buster (Nina's standard weapon).

Stick with:

or take:

Anything that includes a straight frontal shot with maximum range is a good thing. While Star Beam and Forkalator do slightly less damage per projectile than the N-Buster (i.e. 80%), that might not matter much if you mostly use powers against bosses. And the added vertical range sure can come in handy in stages.

Main Weapons (Ace)

Most importantly: Never ever take the axe.

The ©Rippling Axe is the Shadespur among main weapons. Yes, spamming aerials against bosses is strong, but you can and you will lose tons of health in difficult platforming sections (level 9!) due to the stomp attack. Also, the axe's ground attack locks you in place and is inferior to the aerial in every aspect, so it's quite useless. Furthermore, each attack you can perform with the axe makes you stop moving horizontally, which adds up over time, resulting in massive time loss. Never forget what Ace himself said in The Legend of Nina:
https://youtu.be/XUnNBg4ZLOs

A-Sabre:

The A-Sabre is Ace's standard weapon and already really awesome. It has pretty good vertical and horizontal coverage, good boss DPS and is easy to use. There are people who say this is his best weapon, and I cannot blame them.

Most likely, you already know how to use the A-Sabre. One thing though: When fighting bosses, don't mindlessly mash the attack button, or the 1st hit of each of your 3-hit combos will be swallowed by i-frames. Make sure to pause for half a second after each combo (you know you're doing it right if you see a damage number and hear the sound effect for every hit). The same holds true for the spear and the glaive, by the way. Really, keep this in mind or you will drastically lower your DPS against bosses.

Plasma Blender:

This weapon is a literal game changer, because you will play the game quite differently once you get it. If you find it, keep it, and raise your ATK stat as high as possible (at the cost of PWR, if necessary). Get Dracopent's helmet and glove (the pink ones), if possible. Currently, the Plasma Blender is ridiculously overpowered. You will cut through bosses like a hot knife through...air. You won't need to take powers to use as boss weaknesses anymore (except Flameshield to stop Rollster); powers will mostly be used for their secondary effects once you have the Plasma Blender. This is the best weapon for Ace to get in Daily/Weekly Challenges.

Spinning Glaive:

Become a deadly ball of...death with this awesome weapon of mass destruction. Thanks to the coverage of its aerial attack, the glaive lets you kill enemies anywhere on the screen with ease. Combine it with some leg augs to stay in the air longer. The ground attack is not as good as the sabre's, but you will most likely not care about that anyway. I always take this weapon over the sabre.

DPS against bosses might be marginally lower than the sabre's, but the added vertical range will make up for it. Note that the glaive has two different ground combos: The regular 2-hit combo and a slightly stronger 2-hit combo that is only available up to one second after you landed on the ground (after a jump). So the glaive's strongest combo is an aerial followed by two after-landing ground attacks, so start every combo with a short hop and an aerial spin.

Sharp Sharp Spear:

A sharp spear developed by Dr. Brighton Sharp. Or just a really sharp spear? This weapon gives you almost Nina-like horizontal range at the cost of vertical range. DPS is probably lower than the sabre's, but the added range might make up for it (think about Kur, Eternal Star, Vile Visage...). Incredibly useful in difficult hardcore challenges to attack enemies from a distance and avoid damage, but whether you take it in softcore challenges is up to you (as previously mentioned, the sabre is pretty good already and has better DPS). I don't take it in softcore challenges, but in hardcore challenges I usually do.

Powers

As I already mentioned, powers should be an essential part of your play style. Powers have excellent DPS against bosses and some amazing secondary uses. There is never any game mode or skull that will remove powers or NRG drops from the game, so you can tell the developer wants you to use them.

Not all powers are created equal though, and some are much more useful than others. In this section you can read about my personal power recommendation.

First of all, I suggest you use the default power selection mode with three slots, not the power wheel or the cycle mode. This way you can quickly use three different powers and don't have to go to the pause menu to change them (or, God forbid, slowly cycle through them).

Highly recommended powers:
The following are powers I always take and I urge you to do the same.

Vera

Vera is just amazing, I don't ever go without it anymore. Vera has amazing DPS and energy efficiency against regular enemies and can be fired quickly and precisely. Vera is also essential to protect yourself from Dr. Brighton's Quint Lasers in level 9 and it can help a lot against clones in the battle against Flat in level 10. Last but not least it lets you fly if you shoot downwards, which makes it a useful leg core aug ersatz that lets you save yourself from falling into pits.

Although Vera only deals half the usual damage against bosses, it is still the fastest boss killer because it ignores i-frames. While it is much less energy-efficient against bosses than against regular enemies, you can still use it to deplete bosses' health bars quickly and reliably, assuming you have a lot of NRG to spare. However, Vera deals extremely reduced damage to Vile Visage and Kur, so don't use it against these two (only reflect Kur's Quint Lasers with it). Zephyr makes Vera shoot more bullets per second, but be aware that your NRG will deplete faster as well (when jet-packing too).

Force Nova

You probably guessed that Force Nova would be high on the list, it's usually considered one of the best powers by pretty much everybody. Use the AoE attack to block projectiles around you and kill groups of smaller enemies (especially helpful in Glory Zones). Force Nova should be your panic button – pressing it usually solves all problems in your close vicinity, so always have the power in one of your active slots. Furthermore, deactivating lasers is also incredibly helpful in level 9 and allows for some shortcuts in level 10. I always take Force Nova in my runs, no matter what.

Recommended powers:
Great powers you should consider taking even if you already beat the bosses that are weak to them.

Flameshield

Flameshield is not just useful as a defensive, but it's also quite the good offensive power to deal extra damage when fighting at melee range. However, my main use for it is to guard against annoying icicle shooters. Those are everywhere in high-level Frostor, Finesse Glory Zones and in level 9. Also, the most annoying climbing pattern in the final battle is the one with icicle shooters at the top, so Flameshield can keep you from rage-quitting here. Keeping Rollster from bouncing is also great, but Flameshield is not so useful to attack other bosses.

Splinterfrost

Great straightforward no-frills projectile attack for Nina and Ace. Does pretty good damage on hit – and even if you don't hit, it might shatter at a nearby wall and still kill the enemy you were trying to shoot. However, its greatest feature is the ability to freeze the often-annoying flamethrowers, so make sure to pick it up if you are facing a high-level Agnisort. Splinterfrost is also a pretty decent all-purpose boss killer if you don't have the boss's weakness, so I recommend it especially for Nina.

Quint Laser

I mostly play with Ace so I have no use for this slow-ass weapon outside of the fight against Shatterbeak. However, it does have a pretty good damage-to-NRG ratio, and if you play with Nina, you should absolutely take this weapon and use it against Dr. Flat. In the section "Dr. Flat Strategies" I explain in more detail why I recommend this weapon so strongly for Nina. If it weren't for Dr. Flat, Quint Laser would be part of the following tier.

Good powers:
You should take these powers if the bosses they are weak to are still ahead of you. Nina might also need at least one energy-efficient power to fight the bosses you don't have the weakness for, so besides Splinterfrost and Quint Laser that would be the following two:

Boomerang Blade

Great all-around weapon. Can be shot in eight directions and is the most energy-efficient power of them all if you aim it so that it multi-hits your target. Multi hits against stage enemies with Boomerang Blade also have the best DPS after Vera.

Mortar

Pretty good damage, although it's more useful at the beginning of a run than later because the explosion damage doesn't scale (always deals a flat 40 dmg). However, the trajectory is pretty awkward and will often require some repositioning when used in stages, which will cost you a lot of time. But bosses are not very hard to hit with it for the most part.


Situational:

Shadespur

Mediocre damage, hard to aim and the power icon doesn't even make any sense. Shadespur can be shot through walls and multi-hit enemies, but the farther away they are, the less chance you have of doing so. Even the interaction against Perforator, the boss that's weak to it, is bad, because Shadespur knocks her out of the center position, which is the easiest of her attacks to dodge. The power's secondary effect—solidifying yoku blocks—is 'meh' at best. I never take this power, ten nuts are always more useful in my opinion. Feel free to disagree and let me know why you think I should give Shadespur a try.

Power Chart

The following power chart will let you calculate how much damage you can inflict with each power per NRG unit. It's a bit technical, so you don't necessarily need to read through it, but it's here for reference.

To calculate the damage you inflict with a power per hit, you will need to add 10 to your current PWR value and multiply that number with the damage multiplier that is listed in the chart. For example, if your character has 3 PWR and you shoot an uncharged Quint Laser, that projectile will do 65 damage --> (10 + 3) x 5

Projectiles per NRG simply tells you how many projectiles this weapon will produce per NRG unit. Except for Vera, one press on the power button will cost one NRG unit.

Potential damage per NRG indicates how much damage you can deal with the respective power to a single enemy per NRG unit. It takes into account multiple projectiles or a power's capability to hit the same enemy multiple times. The number you see in that column will have to be multiplied with (10 + PWR) as well to get the actual damage.

Power	Damage multiplier	Projectiles per NRG	Potential damage per NRG	Additional information
Boomerang Blade	2x	1	2x to 14x (enemies) 2x to 6x (bosses)	Can multi-hit stage enemies up to 7 times and bosses up to 3 times. High DPS.
Quint Laser	5x (no charge) 7.5x (level 1 charge) 10x (level 2 charge)	1	5x to 10x
Vera	0.6x (enemies) 0.3x (bosses)	10	6x (enemies) 3x (bosses)	Best DPS. Consumes two NRG units per second at default attack speed but gets faster with every Zephyr you pick up. Does only half the damage to bosses, and only 1/10th to Vile Visage and Kur (but you can reflect his bullets). When calculating the actual damage, note that damage numbers are always rounded down to the next integer. So if you have 16 PWR, each Vera bullet should technically do 7.8 damage against bosses, but damage only shows up as "7". I don't know whether the game internally takes the additional 0.8 into account.
Splinterfrost	4x (big shard) 2x (smaller shards)	1 big one 9 small ones	2x to 6x	Bosses hit by the big shard sometimes also get hit by a smaller shard of the same shot (especially Vile Visage, Kur and Rollster).
Mortar	4x + [40dmg]	1	4x + [40dmg]	Ignores shields.
Flameshield	2x	4	2x to 8x
Force Nova	3x	1	3x	Hits all enemies around you.
Shadespur	2x	1	2x to 6x	Can multi-hit nearby enemies up to 3 times I think. Not far-away ones though, and you will usually miss them anyway.

(I will add a table with main weapon multipliers in future versions of this guide.)

Augments

In this section, I will give tips on what to buy in stores and what not. There are also two augs I urge you not to take, even if you find them "free of charge." This is not a comprehensive augment list and I will only talk about certain augs/aug groups. If an aug is not listed here, that means I don't consider it especially useful nor harmful.

For a full list of augs and what they do, please refer to this excellent guide by Cirom: https://steamcommunity.com/sharedfiles/filedetails/?id=575558803

Health/armor items:

Do not spend your nuts on health items when playing softcore challenges. Pick them up if you see them somewhere for free (bonus chests), but do not buy them. You shouldn't lose that much health in the first place, and whatever free max health augs the game throws at you should be enough for a regular Daily Challenge. The only exception is if you have picked up multiple health-lowering items and you have a max health lower than, let's say, 6.

ATK- and PWR-increasing items:

Buy as many of these as you can. If you have to decide between ATK and PWR, buy whatever you mainly attack bosses with. You want to be as strong as possible, and you need to reach a certain attack or power level to efficiently fight the last boss.

SPD items:

Get your SPD up to 8 as soon as possible. There is a softcap at 8, so having any more speed than that doesn't seem to have any significant impact anymore. However, Oxjack's helmet is not affected by this, so you can always add it on top.


Forcemetal Shell lowers your speed by 2. Picking up one is like not taking a Ninja Sash. Therefore only pick it up if you have 10 or more SPD.

NRG items:

The basis for all power usage, so raise your maximum NRG as high as you can. 20–25 max NRG is a comfortable level, but don't stop here if you can afford it.


Yeah man, that's the stuff. NRG-replenishing augs are great and necessary for power builds. Get Spillover Matrix and Enerative Plating in stores if you see them, as they only appear once per run.


A special shoutout for Forgotten Memento. This aug lets you use nuts to fuel your powers once you have run out of NRG. Forgotten Memento will let you use 2 nuts instead of an NRG unit. This is very useful for those runs that don't give you a lot of max NRG. So if you have money to spare, why not burn it?

Deez nuts:

Get as many of deez as you can, preferably early. Both items will increase your total amount of nuts throughout the run. They cost only 12 and 20 nuts respectively in stores, so unless you buy them really late, you will get that money back in easily.


Hoarder's Might is ridiculously powerful. For every 20 nuts you own, both your ATK and PWR stats will be increased by 1. That's about what you'd pay if you consistently bought an equal amount of ATK and PWR upgrades. Absolutely overpowered item, I strongly recommend you buy it. If you also have a Nut Replicator, you might want to be as frugal as you can to get as many nuts per level as possible.

Repros:

>>>
Repros will do a lot of extra damage to bosses and increase your DPS. Tiny Flamespewer is my favorite due to its high close-range damage, but I'll also get the others if I have the chance.

Repros become stronger the higher your ATK and PWR values are. Tiny Flamespewer and Shockwave Sidekick do damage based on your PWR value, Murderdrone and stupid Re-Flapp become stronger the higher your ATK is.


Buy this coin if you already have some Repros or if you have money to spare. It will increase your Repros' damage by 25%.

Miscellaneous:

Thrillseeker makes sure that there is a Glory Zone in each of the following stages. Buy it unless you are already in level 8 or higher.


The Volunteer turns all in-level stores into Very Safe Labs. Prototypes are rarely useful (see below), so you definitely don't want this aug.


World Slug has zero benefits in my opinion. Platforming segments don't really become easier, and often you have to wait longer than usual for platforms to progress. It's actively detrimental, so don't ever pick it up.


The mushrooms give you the best bang for your buck. Buy them even if you have Hoarder's Might. You will get the same amount of ATK and PWR back that you lost through the spent nuts, but you will gain SPD and JMP on top of that.


Choicebooster will increase the amount of items in future stores. Needless to say, buy it if possible, otherwise you might miss your chance to buy something awesome later on.

Prototype Augs

This is going to be a short section. There are only two prototype augs I recommend you to take, and only under certain conditions.


Uncharging Force makes you unable to charge up your main weapons, but gives you a flat +7 ATK. Do absolutely not pick this up with Nina, but for Ace it's generally useful because you will mostly use his basic attacks anyway (or at least, losing the ability to charge the sabre/spear/glaive is not the end of the world). Note that your Plasma Blender (and Axe) as well as the full Dracopent's set's permacharge are unaffected by this aug.


At the start of each new level, you will gain +2 ATK and +2 PWR. This is obviously pretty awesome, but take into account that you will lose 2 max health as well, so it's a very risky Prototype. If you have lots of max health already, pick it up by all means, but if you see it with base HP in the first level for example, you might end up with 1 max HP by the time you reach level 5, and only RNGesus can save you then. Your choice.


All other prototype augs are mainly useless for challenge runs. Nothing that limits your use of powers is worth it, nor do you want to take double damage or lose your ATK power completely. Zookeeper's Burden, the aug that removes all your attacks and powers but gives you one of every Repro, will make you super slow, so it's absolutely not worth it. Sanity Converter, which doubles your PWR damage but makes you consume max NRG, might be useful if you could pick it up in the final level, but unfortunately the last Very Safe Lab can appear in level 8.

Needless to say, if you play the Weekly Challenge and you know a System Restore is coming, you might pick up any of these as you see fit, but in a Daily Challenge you should never count on it appearing (the chances are like winning the lottery).

Core Augments

In this section, I will rank the core augs of each set per category (e.g. best to worst helmet). However, that doesn't mean you should always take the better-rated core aug over another one, because you might want to assemble a complete set (the only useful sets for challenge runs are Owlhawk and Dracopent though). So it's always a decision you have to make whether to take a more useful core aug for that slot or to try to complete a set.

Helmets:

>>>
Owlhawk's helmet is usually king, since an increased NRG pool is beneficial for 99% of all builds. Dracopent's helmet is more useful for Nina than for Ace. His DPS against bosses is higher when doing uncharged combo attacks, whereas Nina should attack with charged shots only when she has this helmet. However, when you have the Plasma Blender as Ace, Dracopent's helmet is the best helmet to take, as it will make the Plasma Blender shrink much more slowly over time and you will have less use for the increased NRG pool that Owlhawk grants.

Oxjack's helmet used to enable Boltdash in the past and I used to rank it as top-tier. Nowadays it enables the Dashbolt, which will fire a projectile upon dashing on the ground. Its power scales with the speed stat (15 + 3*SPD), which makes it somewhat special, but usually it's not worth taking over Owlhawk or Dracopent because even at unreasonably high speeds it won't deal considerable damage. However, this changes when you have the Cranial Resonator (the item that improves helmets' capabilities), because the tripled Dashbolt damage is a force to be reckoned with. High SPD + Cranial Resonator + Oxjack's helmet is a very rare combination though, so you will most likely only see this in weeklies when you're actively working on that build.

Armatort's helmet is mostly useless for score runs though, take it only if you have nothing else.

Chestplates:

>>>

Oxjack's shield can be used to block annoying projectiles in narrow spaces and to make some boss fights—like the Twins, Perforator and Vile Visage—a breeze. Note: you cannot block Kur's Quint Laser shots with it.

Armatort's body prevents knockback, which is only marginally useful since you're not going to be hit much anyway. And don't even think about damage-boosting! It's never worth the 10 point loss.

The other two chestplates just replenish your HP, so they are mostly useless in regular Daily/Weekly Challenges, but you might want to keep them for the full set. I always take the Dracopent armor over all the others when playing with Ace, unless I know that getting a full set will not be possible anymore in this run.

Gloves:

Ace:
=>>

Nina:
=>>

It's kinda hard to rank the arm cores because it strongly depends on what build you're going for, so their usefulness will vary significantly each run, and also between the two characters. Owlhawk's glove occasionally recharges NRG (15% chance per ATK kill) and increases your PWR by 4, so it's the best weapon for a power build.

The additional charge level you get from Dracopent's glove is kinda nice in stages, but basic attacks (or first-level charges with Nina if you have Dracopent's helmet) are still more efficient against bosses. You will only use the ultra charge as an opener. The exception being the Plasma Blender, get this glove when you have the Plasma Blender! Other than that, Dracopent's glove increases your ATK by 4, so I often buy it just for that.

The quick charge from Oxjack's arms is very useful for Nina to increase DPS against bosses if you have to fight them with your main weapon for whatever reason. It's especially useful in combination with Dracopent's helmet. However, for Ace I'd still go basic attacks all the way. This glove increases both, PWR and ATK, by 2.

Armatort's shot cancelling is quite useful for Nina and can do a similar job as Oxjack's chestplate with the shield. However, for Ace it's much less helpful because his charge attacks are so short. You can still use it to cancel individual boss projectiles. It's quite good in combination with the Plasma Blender though, because keeping the charge alive on a boss is like having a constant shield in front of you. I should mention that the Axe in combination with Armatort's gloves is also excellent against all bosses that rely heavily on projectiles, but since you're never going to pick up the Axe, it's pointless to talk about it.

Boots:

>=>

Dracopent's boots are the best boots for challenge runs, hands down, as they offer maximum speed with pretty good mobility. Owlhawk's flight offers the best mobility, but it limits your speed so you will lose a lot of time in the long run compared to Dracopent. Oxjack's airdash is just as fast as Dracopent, but it controls like a$$. Armatort is slow and offers no vertical mobility whatsoever, so it's the worst pair of boots for challenge runs.

Set bonuses:

=>>>>>>>>>>

Forget about the Oxjack or Armatort set bonus, they are pretty pointless and you should never actively try to complete these sets. Instead, if possible, assemble a Dracopent or Owlhawk set (ATK and PWR build, respectively). I don't think I have to explain them much. The full Dracopent set lets you spam charged attacks, whereas the juiced powers you get from Owlhawk's set gain new effects or do more damage. The damage boost of Vera and Quint Laser is especially useful against bosses.

Hardcore Challenges

Hardcore challenge runs are much more versatile than regular challenges and, no surprise here, usually (much) harder. Each skull combination makes for a different run, but I will give you some tips for each individual skull.

Note that you can ignore my earlier advice about not buying health items when you play hardcore challenges. Buy as many health upgrades as you feel are necessary, as the hardcore challenges are often purely about survival and there will be a lot fewer finishers than usual.

Easy skulls:

Marathon:

Marathon, by itself, is not a hard skull. It makes stages longer and therefore increases the amount of bonus paths. The larger quantity of enemies you encounter will also increase the amount of drops. Not much to say here. And that's it already with the easy skulls.

Medium-tier skulls:

Undying:

Undying is a pain. Regular enemies take forever to kill, especially in the beginning of a run, so you may want to get your ATK value as high as possible early. Bosses will also take much longer, so if you're someone who tanks bosses a lot, then you will have quite a bit of trouble with this skull. Get some boss practice if you need to.

Bosses with spawns, namely Vile Visage and Death Lotus (Eternal Star not so much), are especially hard because their spawns also have double health. If you encounter a medium-to-high-level VV with a weak Nina, you will have to mash that attack button hard to kill the flying teeth before they completely fill the room with explosive spiders (which of course also have double health). Also, the Lotuses in DL's room have 40 HP now and will therefore most likely not be killable with a single charge shot. It's going to be much harder to keep the room clear of them and still focus on the boss. Be aware that you might lose more health than usual against these two bosses and prepare accordingly.

Note that regular enemies will award twice as many points when Undying is on, so as tedious as it may be, kill them all! A much larger portion of your score will come from enemy kills.

Purist:

Purist means no jump or speed upgrades and no core augs. Sounds harder than it really is. Glory Zones will reward you with regular augs now, which is not a bad thing at all, as you can get quite the good stuff, which often makes up for the absence of core augs. And if you've been following my previous advice about always taking Vera, you are well prepared for any platforming, since Vera will be your poor man's leg upgrade for this run.

Swarm:

Mo' enemies means mo' trouble, especially in Frostor because you will see more annoying shield beetles shielding other annoying enemies. I can't really give you much advice for this skull, but you will most likely be fine due to the larger amount of drops.

Stone:

Stone is the – thankfully – toned-down version of Rock, which used to suck a lot of fun out of Hardcore Challenges. With Stone, you will lose 4 HP when falling into pits or when touching spikes, lava or lasers. That basically means you're losing 40 points! And you don't want that, so be extra careful to avoid these hazards. Make sure to get Force Nova to deactivate lasers and buy Gapminder if you can to neutralize damage from pits. You might even want to take Armatort's legs over Oxjack's or Dracopent's because it's a lot safer to maneuver through difficult platforming areas.

Stone doesn't make the game harder in terms of gameplay, but you will get hella nervous around the respective hazards. And somehow my character is always magnetically attracted to them when Stone is active.

Furor:

Enemies like turrets will do their attacks at shorter intervals and penguins will fly faster. The enemies that become significantly more dangerous with Furor are the Skytemple cannons and the shield beetles in Frostor. The cannons will shoot at a much faster rate, so make sure to approach them when their tip is not pointing at you, as you might not have enough time to dodge. Kill them fast because once they started shooting you're in for a lot of trouble. The shield beetles will lower their shields for a much shorter time, so make sure to restrain your muscle memory or otherwise you will hit their shields, which will make them retaliate with laser attacks.

Only a few bosses actually become harder with this skull, worst of them being Shatterbeak. He will dash through the room at insane speeds and you will barely have time to attack him when he pauses. Make sure to pick up Quint Laser or some shield-y powers like Force Nova or Flameshield. Also stack up on health and armor before fighting him if you can. I'm not kidding, the Shatterbeak fight becomes absolute madness.

When Fighting Kur in a Furor run, be aware that his ground dash will be much faster. You might still be able to react in time and jump over it, but a safe strategy might be to stay on the first platform.

Death Lotus' spawns will shoot more frequently but also a bit sooner after they spawn.

Last and also least is Rollster. Furor actually makes him a bit easier imo. His regular "walking" speed will increase so that his first form will always get stuck somewhere at the upper platforms. He'll never come back down to the bottom floor before splitting, so it's safe to stay there during this phase. I'm not 100% sure, but I think his bouncing attack is actually not affected by Furor.

Toxin:

Toxin activates a time limit for every stage. If the timer runs out, the deadly neurotoxin kicks in and you will lose 1 HP every 10 seconds. Note that the Toxin timer deactivates upon touching the first boss door, so once you get into the pre-boss room, you're safe. You can take as much time with the boss as you want, it will not affect your score at all.

You will not get speed bonus chests at all when Toxin is active (that means less loot and fewer augs in total), but you will get the time bonus points if you make it through the stage within the time limit.

Toxin is actually quite a hard skull, but it's neutralized easily with speed items. So the first order of the day is to increase your speed. However, before you get any speed upgrades, you will have to make some sacrifices and NOT take every optional bonus path and/or Glory Zone in the level. Let's say a level has 2 bonus paths and a Glory Zone, then you might have to skip at least one of the bonus paths. You can also make an estimate on how long Glory Zones will take and whether you still have enough time. For example, a Finesse Glory Zone might take much longer than "Lock the Blocks."

Needless to say, this skull becomes harder in combination with certain other skulls, mainly Undying or High Tide. You do get a little more time when those skulls are active, but not much.

If you do run out of time at some point, the best advice I can give you is to stay calm and keep a clear head. Think about it, if you still have 6 HP, you can play for another whole minute. In that time you might find more HP and you can play even longer. If, on the other hand, you panic once the timer runs out and start making lots of mistakes, your fate is sealed.

Since the bonus timer stops at the boss door, you can take as much time for the bosses as you want. So if you feel confident fighting bosses, Defiant Decree, the prototype aug that increases each boss's health by 50% in exchange for an additional reward chest, becomes a valid option for Toxin runs.

Hardcore Challenges (continued)

Hard skulls:

Wrath:

Wrath is a hard skull in my book. Enemies (and, unless this was changed at some point, also flame shooters) will deal double damage. At first, you might think that that's not much of a problem, but wait until you get a double whammy from an enemy that now deals 4 damage. As with many other skulls, Wrath is more of a problem in the beginning than later (when you have acquired several max health items), but losing at least 20 points every time you get hit means you should be more careful around enemies throughout the whole run.

High Tide:

High Tide steps up the level generation, meaning you will basically play through levels 5–14 instead of 1–10. Harder enemies and platforming sections will appear earlier than usual.

This skull is most difficult in the beginning of the run, because you're practically thrown into level 5 at base stats. The hardest part is beating the first few bosses. Don't forget High Tide will be combined with two other skulls. Can you beat a level 5 Perforator at double health (Undying) that does double damage (Wrath) while having little to no upgrades? If not, do some boss rush practice WITHOUT AUGS. Really, it helps. Just try beating boss rush mode without picking up any augs. If you can make it past the first 8 bosses consistently then you're well prepared. Make sure to also vary the boss order so you don't just beat the hardest bosses first.

Another thing to remember about High Tide is that from level 4 onwards you will fight bosses in their hardest form (which you usually only see in level 8 of a normal run). So get comfortable with the idea of fighting floorless Death Lotus, a Rollster that splits more than once and Eternal Star with white exploding bats.

Famine:

Famine, or the quest for health-replenishing items. When Famine is active, no HP will drop and no health vending machines will spawn either. However, armor drops are unaffected. Famine is all about saving up your money to buy one of these items:

>>>

And these are fine too:


Body armors all cost 30 nuts, so make sure to have that much ready in case you see a Dracopent or Owlhawk chestplate in a store. Make sure to not skip Glory Zones either, even if Toxin is on. The Dracopent chestplate means that the dangers of Famine are pretty much neutralized, but the other items listed here will make your life much easier as well.

One item becomes absolutely worthless in Famine runs:

I guarantee you it appears in a Glory Zone in every single Famine run. Be prepared to raise your fist and curse at the heavens when that happens.

Bankruptcy:

Last but not least is bankruptcy. It removes all nuts and all nut-granting augs from the run. Vending machines will not spawn either, so you cannot even knock them over with Quint Laser. As a result, there is nothing you can buy in stores, so you will have fewer augs in total throughout the run. This skull is totally devastating in combination with Famine. There's no real strategy for it, you'll just have to be good at the game when playing with few augs. Praying to RNGesus won't hurt though.

Enemy Score Table

The following table shows how many points each enemy awards upon kill. The amount of points is basically the HP of that enemy divided by 10, rounded up to the next integer. Most enemies have three versions: Alpha, Beta and Gamma (easy, medium and difficult version).

If I ever have time, I will add pictures of each enemy version to this chart, but for the moment the images from the Datalore will have to do.

	Alpha	Beta	Gamma
	1	1	2
	1	6 (2 x 3)	5
	5	8	13
	2	5	10
	5	7	13
	3	5	12
	5	8	15
	4	6	12
	3	5	10
	2	4	6
	5	10	30
	2	4	8
	6	9	17
	3	6	13
Lotus	2
Visage's teeth	8
Cerby (Dr. Sharp's pet)	210

• When an enemy becomes a soul enemy (= glowing, faster, much more health, drops Soul Chips or golden nuts), it will give three times as many points. The exception being enemies that normally award 3 points, they will award 10 points as soul enemies.
  
• When the Undying skull is active, all enemies will award twice as many points. The exception being Flapps, which will award 1/1/3 (Alpha/Beta/Gamma). For example, when Undying is active, a soul Gamma Snomp (the tri-headed snake) will award 180 points (30 x 3 x 2).

Dr. Flat Strategies

Dr. Flat is different from other bosses in that you cannot constantly attack him throughout the fight. You have to traverse the boss room, which is lined with varying hazards, multiple times before being able to attack him. And each time, you only have a couple of seconds to deal damage before having to go through another hazard gauntlet. This battle is a science in itself, so it deserves its own section in this guide.

The exact way it works is this: Each time you attack Flat with a main weapon, a power or a close-range Repro (i.e. Tiny Flamespewer or Re-Flapp), you have exactly three seconds to keep attacking him until he walks over to the other side of the room. However, if you manage to deal damage equivalent to 1/5 of Flat's max HP within those three seconds, he will switch sides sooner. That means that in the vast majority of cases, you will need at least five phases to beat him. (There are ways to beat him in less than five phases, but you need to be incredibly strong to do that; I will mention how to do it below, but it's not realistic to achieve this in regular runs.)

By counting damage in one of my gameplay recordings, I was able to narrow down Flat's total HP to something between 2880 and 2990 HP. Zero, another 20XX addict, claims that Flat has 2890 HP, so let's just go with that. That means in order to beat him in five phases (each phase takes about 20–25 seconds by the way, with the danger of you taking damage somewhere in the boss room, so we do NOT want the fight to last longer than five phases!), we would need to deal 578 damage per phase. However, the first attack you execute on Flat per phase will always deal an additional 100 damage, courtesy of the dev! This is to ensure that the fight doesn't take forever (i.e. not longer than 29 phases, ha ha), even if you're extremely weak for whatever reason. So, technically, you need to deal only 478 damage per phase.

For reference, in three seconds Ace can do four full 3-hit combos with the A-Sabre and Nina can shoot six times at Flat. Assuming the first attack is charged, I calculated how much ATK you would need to achieve this much damage (without Repros):

• To do 478 damage with the A-Sabre (four full combos, first attack charged), Ace would need at least 21 ATK. This is a standard value and pretty doable, meaning usually you can use the A-Sabre to kill Flat in five phases. It'll be even easier with the Plasma Blender.
  
• To do 478 damage with the N-Buster (1 charged shot and 5 lemons), Nina would need at least 59 ATK! This is an extraordinarily high value and you will usually not achieve this.

You see that Nina will either have to rely on Repros or use powers to deal 578 damage. I currently do not the Repros' exact DPS, but it is much safer to rely on powers than Repros anyway, because they (the powers) are something you can always get in a run.

I'll do the math for you for Boomerang Blade and Quint Laser:

• Boomerang Blade: You need to shoot three Boomerang Blades at Flat from the far end of the platform next to him. This way you can hit him up to 6 times. You already know how to calculate this yourself, but I did the math for you: You need at least 30 PWR (6 * 2 * (30 + 10)). However, the Boomerang Blade method can be dangerous to use because you need to shoot Flat from the far end of the platform and there are often flamethrowers or icicle shooters shooting at you. Furthermore, from that distance, your Repros cannot support you.
  
• Quint Laser: You can hit Flat with one fully charged Quint projectile followed by two uncharged Quint projectiles from up close OR four uncharged Quint projectiles from a bit further away on the platform (far enough to be able to cast two Quint projectiles in a row before the first one hits him). Both methods will deal the same amount of damage, but the first one (at close range) will cost one more NRG unit, however it is also safer and your Repros can support you. So, to reach the optimal damage with Quint Laser you need only 14 PWR! (*pogchamp*).

You see, Quint Laser is the way to go for Nina. Note that you would need 25 NRG if you use the close range method at 14 PWR. However, it is more likely that you have something around 30 PWR at the end of your run, so you'd need less NRG than 25.

Beating Flat in less than 5 phases

With everything that you learned in this section, you might have figured out yourself how to beat Flat in less than four phases. To do that, your very last attack in a phase needs to deal enough damage to considerably exceed the 20% max HP limit. So for example, you Vera'd Flat down for 19% of his max HP and then follow up with a last strong Quint Laser that deals 6% of his max HP, making him lose a total of 25% of his HP in this phase. This way, you could kill Flat in four phases. Or, less tediously, you just blow him away with ridiculously powerful Quint Lasers (augmented by prototype multipliers) in three or fewer turns: https://youtu.be/AXqQUMmZWi8
You will very rarely get this powerful though, so I don't recommend pursuing this strategy in a Daily Challenge. And it requires too much math!

Some random tips for Flat

• Lasers you deactivate in the boss room with Force Nova will stay deactivated for the rest of the fight. While there are multiple segments with lasers at similar positions, it might seem that they have re-activated, but that's just an illusion. Each deactivated laser will stay deactivated in that respective segment. Flame shooters will not stay frozen though.
  
• I haven't verified this, but I assume that the bonus timer (which is hidden in level 10) stops the moment you kill Flat (just like with any other boss), so you can take your time in the escape sequence (those explosions are not really a threat anyway). You also can't lose any more points by taking damage during the escape sequence, so it's just smooth sailing after you have beaten Flat.
  
• Flat's UI health bar is hidden, but the lights at the bottom of his glass cabin indicate how much health he has left (they also change color from green to yellow to red).
  
• If you have Murderdrone and/or Shockwave Sidekick and you DON'T have Tiny Flamespewer or Re-Flapp, you can stand right next to Flat's cabin and let them attack him without triggering the 3-second time limit. However, Flat will switch sides after 5 minutes by himself. I have never checked if this method will kill him faster than when you do it "manually," but I sure hope it doesn't.
  
• You get one point for every Nina or Ace clone you kill in the boss room. Since Flat will always spawn new ones each phase, you could potentially get an infinite score during this fight. However, you do not want to kill Flat, so you shouldn't attack him at all. This means you have to wait 5 minutes for each phase to end by itself. So, assuming 5 clones spawn on average per phase, you'd get 1 additional point per extra minute that you stall the fight. So if you start playing the Daily Challenge right at the moment when it first becomes available, you could stay in Flat's boss room for about 23 hours before the Daily resets. In that time, you can get 1380 additional points (23 * 60) by killing clones. However, you'll lose your time bonus (about 130 points) and you cannot get hit in those 23 hours at all or your efficiency bonus decreases (you can lose up to 500 points). And you cannot eat or sleep or you'll lose valuable time. You also don't want to stay much longer than 23 hours, because then the next Daily Challenge will have started and nobody will notice your glorious score anymore, so make sure to wrap up before that happens. But you do see the potential for the Weekly Challenge, right?

Closing Remarks

I hope this guide has been helpful to you, but let me know if you still have any questions related to challenge runs, and I will try to answer them or even add that information to the guide. It's totally possible that I forgot something.

You can also let me know if you disagree with some of the advice I give and have better strategies for certain parts of the run. Thanks for reading.

Thanks to Zero for initial feedback on my guide.

P.S. Some shameless self-advertising: Here's a link to my Youtube channel, where I publish recordings of all my Daily and Weekly challenge runs. Maybe you will find watching them helpful. However, I'm currently abroad and without access to a PC that is good enough to record gameplay, so I am not going to add any new recordings for a while.

[Endarire]

As Nina, I've gotten to level 9 twice just with basic attacks. Sometimes it was 4-way shot and sometimes it was 3-way shot but the only special weapon I used was Kur's Laser to break vending machines.

Thankee!

[jeapie]

A bit late. Just a bit.

However I still want to thank the author LVL99 for sharing some of the wonderfull knowledge shared above. Especially the information give on the last boss.

Thanks,

[LVL99]

I was planing on revising my criticism on Shadespur, especially since I have found new love for it as main weapon for Hawk. However, it will most likely not go into the "always take" category.

[Novus Ordo Seclorum]

ALWAYS take Shadespur. ALWAYS.

[LVL99]

2/2: Say you pick it up in level 7 and the only three extra augs you get from the bosses in levels 7–9 are two useless health items and a Band of Might. Or there might be other stuff that you don't need at this point anymore, like extra SPD, max NRG, a Shinier Token or a Nut Replicator. But those are just a couple of bad-case scenarios, like I said it could go either way.

However, that gave me an idea about where good players might get a considerable edge out of it: Toxin runs (preferably without other skulls that make boss fights harder like Furor, High Tide or Wrath). With Toxin, you don't have to deal with the potential time loss because the timer stops before the boss. I will add that to the guide. Also, Defiant Decree could serve as an extra source for much-needed augs when Bankruptcy is active.

[LVL99]

1/2: Given how rarely Defiant Decree appears, I haven't played enough comparative runs with and without picking it up, and I probably never will at this point tbh. But it does seem to me that it could go either way, depending on what augs you get. My educated guess is that a Defiant Decree in level 1 could increase the total time spent in boss rooms by 1.5–2.5 minutes (worse for Nina than for Ace), so whatever augs you get need to make you this much "faster." And think about the potential extra damage loss.

I'd more willingly recommend it if it weren't for Dr. Flat. Even one potential extra phase as a result of Defiant Decree would be risky. And the later you pick up Defiant Decree, the less you gain from it, because the extended fight with Dr. Flat will always be at the end.

[Zero]

For prototype recommendations, I actually find Defiant Decree almost always pays off.

[Epicwindow+-]

lmao that clone farming strat such evil

[SolarFlar3]

Wow. Thank you so much for this! I haven't played 20xx for a little while, but I'll probably boot it up today to give it a go.

[Zero]

I got a shoutout! Anyways, I can confirm that the bonus timer stops when you kill Flat. A glitch made it stay for client.

Also, I have more than a few points to address regarding some recommended augs. Hit me up on Discord and I'll go into detail when I'm free.