You get a score for each kill and this is influenced by:
1. How many unspent resources you currently have 2. How many cores in your housing 3. Whether or not the kill occurs within the area of a score boost tower 4. Whether or not the kill occurs within the special resource weapon area of effect 5. The value of the alien (not all are the same)
Score boost towers (which are only available Level 8 onwards) provide a 25% boost to the score of a kill, so you want to try to get all of your kills in the area of one of these boost towers.
Don't get too hung up on losing a few cores temporarily, you can lose a few for a small period of time, but realize that all kills will be decremented by 0.02 * (# of cores missing) while the core is not in the housing.
IT IS REALLY BAD to have most if not all of your cores missing when getting kills. So you need to engineer most if not all of your kills before the aliens take the cores. This is not possible with the pods, so it's imperative you focus on killing the aliens released by Pods very quickly.
Resources influence your score the most. Resources accumulate with: 1. Time. Every "tick" you get 10 more resources 2. Waves. Every few waves you'll get a nice bonus of resources 3. When you employ the resource special weapon, you get a nice bump in resources
It's important to try & builld this up. Early resources compound much better than late resources.
Strategy for a high score:
1. You want each alien to travel as far as possible before you kill them so you can accumulate more resources. 2. You want to kill them within a score boost tower's area of effect 3. You want really valuable enemies to be killed while you have your resource special weapon active. 4. Buy new towers only when necessary to prevent cores from escaping. 5. It's better to buy a new level 1 tower if that's all you need rather than spend a lot of resources upgrading an existing tower. 6. Don't kill seekers early. You lose out on points for killing all the little brethren they disgorge. You want to kill seekers LATE.
NOTE: Tower upgrades that you recieve after completing each level will greatly influence your ability to kill things with less cost. The more tower upgrades you have, the more effective your towers can be, and the fewer you will need to build. Therefore it is much better to try to get high scores once you've collected a number of these tower upgrades.
Tower Upgrades can really influence your score. While some towers become more powerful, there are certain upgrades called "Priority Target Strongest" which are available on several towers and are imperative for really high scores. This is because if you have a group of several aliens, these towers will whittle each alien down incrementally to a sliver of health before actually killing them. This allows aliens to live longer while becoming susceptible to area effect weapon such as concussion or inferno in your kill zone.
Let's look at a recommended loadout:
Guns: Priority Target Strongest Inferno: Torch Bearer: Additional 20% damage to aliens they touch. Awesome. More damage! Lasers:Priority Target Strongest Cannon: Chemical tipped ordinance: 100% extra damage over time. Temporal: Increased Slowdown Concussion: Fire Bombs: Burn baby burn Meteor: Priority Target Strongest Missle: Chemical tipped warhead Tesla: Only needed on a few levels, and I recommend boost towers with disruptor instead
This is focused on dealing as much damage as possible and spreading the pain out evenly.
Special Weapon Selection
Between the special weapons, I go with the Professor Biels' resource weapon 90% of the time. It is an extra resource generator & as resources impact all future scoring, this is very useful.
However, there are certain levels / waves that are simply unbalanced and the employment of Advisor Zacara's weapon boost can save you a ton of money in upgrades. There are certain levels, where you'd need to spend 3,000 resources upgrading to get the final wave or 2, but utilizing Zacara's special weapon can help you avoid spending those resources, and the benefit of that may outweigh the additional resources gained with Professor Biel's.
When the level first starts, it's all about killing as cheaply and late as possible. Early resources compound over time and the early game (first 5 waves) will influence your score dramatically. It's imperative to find that sweet spot of just enough. Use the backspace key liberally.
I find Infernos and lasers extremely useful during this time as shielded aliens typically don't show up early and damage per cost output is very respectable.
I'm not pathing that much during the early waves as I'd rather let my resources accumulate to gain the extra score for those early, easy kills.
While I am not pathing, I know precisely how my maze will be and I will place my lasers & inferno's where I want them in my maze, even if the maze isn't completed.
Inferno damage output is compounded when aliens need to take hard 90 degree turns in the path of the flame, so sometimes a single gun or empty boost tower can add a lot of damage output to an inferno.
Use the resource special weapon on a crowd early in waves 1-3 to get an extra few hundred resource boost. The big enemies aren't coming for a while and that early boost compounds.
Note: Level 17, Scarce Resources, is a great level to show the power of letting the resource ticks accumulate. That level is so darn long, it's really easy to put a kill zone up early, and see your score, and then move your kill zone back near the cores and see how dramatically your score increases.
The mid-game is all about prepping your maze and getting your kill zone established.
If you're playing on a level with score boost towers, this is where you start putting these down. I personally like to have temporals on these score boost towers, so you need to have saved 550 resources to buy "the score boost basic kit" of:
Boost tower: 50 Temporal: 300 Score Boost: 200
Establishing The Kill Zone
This should be occuring around wave 5-6. You should have an inferno and/or concussion either next to or supplementing this kill zone. The inferno should be on a disruptor boost tower. You want a laser preceeding your kill zone and cannon's after your kill zone to get what escapes.
Don't use guns in your kill-zone! Remember, we're using the Priority Strongest Target option, and this is not a good option in a kill zone as you want things dead or soon to be dead.
Establishing the softening zone
The softening zone is where you're doing good solid damage, but not killing anything. This is where your guns, lasers, and meteors, along with a temporal or inferno, are softening up the enemy. If disruptor boost towers are available, employ them here.
Oftentimes, the softening zone is similar in composition to the kill-zone, and is built because you are focusing on adding just enough damage so the aliens die in your kill-zone, and it's much more cost effective to soften them up with a cheaper tower than to upgrade your kill-zone to level 3 at this point in the game.
Below you can see both the softening section and the kill zone, both of them have score boost towers active, to collect both early kills and late kills:
Also notice placement of the three infernos.
Finding the right cadence for the special resource weapon
Each level is different in DG2, and it's your job to find that sweet spot where every 4 minutes you're getting the big bad aliens to die all together in a nice compact kill zone. This special weapon is very short duration, and it's worth it sometimes to upgrade weapons so that you're killing them all at the same time. It's better to wait an extra 2 minutes to get the more valuable aliens than to spend it early on a cheap set of aliens.
Late game is all about leveling up your towers and picking the right ones to upgrade. I personally like meteors, lasers and cannon upgrades at this point because enemies are getting bigger and have more health & nothing dishes out damage like a meteor. You need to have 2-3 level 3 RED Lasers to help deal significant damage to the big and fast dudes.
This is where the "Prioirty Strongest Target" really shines. This upgrade on the laser increases to level 5 where you're dealing an extra 100% damage! That's like having 2 Red lasers for the cost of 1!
So not only are lasers whittling down enemies, it's dealing a LOT of damage.
Cannons are great for those single big targets. Again, Chemical tipped ordinance gives you an effective 2x the cannon for the price of 1!
Late game is where your pathing is really shining. Having a set of towers that the aliens pass by multiple times multiplies your effective damage. This is where ranged weapons can be much more effective depending upon the map. Placement of weapons so they can fire 2 or more times on the same alien as it goes through different paths is more cost effective than a short range weapon that can only hit one path one time.
Your kill zone should be all level 3's (temporal/concussion/inferno) to deal maximum damage. Your softening zone hopefully is still level 2's.
Don't forget that resource special weapon! Save it for the final wave & collect an extra bounty!
Note: Observing the scoring wave graphic
The scoring wave that is in your upper right hand corner is not an accurate representation of your previous score or another person's score if you are trying to compare while you are playing.
I don't have confirmation of this from HPE, but I can tell you from many, many attempts, and knowing how I play, where I am purposely waiting to the end to kill things, it really appears that the scoring wave is an average of your score over time and is not really showing you an accurate depiction of previous runs.
The only time the scoring wave is accurate is at the end of a wave.
So don't get hung up if you're comparing yourself to a friend or a previous run unless it's at the end of a wave.
Here is proof:
See those? That's me beating my best run, but you wouldn't know it when I'm 100K behind in score! This is because I'm killing so late, and there are 5 waves on the board that haven't scored yet, so HPE is averaging my score over the wave!
Building new towers does lower your efficiency a little (by 25% of the tower cost).
I have to disagree with this as I've done some extensive testing with Gun and Laser towers, from a "DPS / Cost" perspective, and it's really a wash on which towers are better. I had originally thought that Level 3 towers were the cat's meow and would be more efficient, but that theory was thrown out with the bath water when I looked at the damage over the entire round to see if it was worth it to upgrade for additional DPS.
Let's look at gun towers: It takes 6.8 (we'll round up to 7) level 1 guns to have the same damage as a level 3 gun.
If I have 7 guns and sell them, I end up with 75*7 = 525 sell value - with an investment of 700 If I have one level 3 gun and sell it, I end up with 525 sell value - with the same investment of 700
So it's actually no difference and tower count does not contribute to efficiency, all things considered.
However, don't think that it's worth it from a cost perspective to create longer mazes. Bathosfear did some testing[forum.hiddenpath.com] & while I didn't rigorously test it, his observations confirm my suspicions throughout all my runs at getting high scores.
A story for how I achieved #1 (for a bit anyway) on competitive
I was going through competitve, slowly making my way. I had achieved a few good scores, some top 10 and even got #2 on Level 7, Split Decision.
A few notes on competitive: 1. No tower upgrades, No special weapons available 2. Boost towers are available with the score wave 3. Somehow it appears that HPE is keeping the cheaters out of these. That's a relief.
When I got to level 9, Precipice, my first score "ok" at about 39th, but the leaders were so far in front of me, by over 70K score! I knew they had a trick up their sleeve. My first foray into this was to try a minimilist approach, loading up the curve with temporals and concussions with a few missiles for backup.
But the top scores were still way over me, and I got to thinking of two things:
1. Seekers 2. Need to put the kill zone further back
Seekers generate enemies and if you kill them early, they won't have disgorged all of their little ones, so it's imperative that you let them live for a long time before killing them.
Moving the kill zone back was easily doable, but I ran into a problem, some of the toughest waves were when the slow lumbering dudes got overtaken by the wave behind them. This caused all my towers to focus on the new arrivals instead of the larger guys that just weren't taken out. So I had to devise a path and solution.
And after many, many hours (4 hours alone on this one), and many attempts, here is what I ended up with. This is any early shot, just forming the maze.
and how it looks near the end:
This is a very touchy layout. Lots of back-spaces to add just another tower. I also had to spread out the score boost towers as I couldn't reliably kill things in one or two places.
And the result, well, for now at least, I have the top score ;-)
In summary, this points out that I left an easy 75,000 worth of points on the table by putting my initial kill zone up front. By moving it back, I got more ticks of resources, and the seekers were able to get all their children disgorged.
Ok, this is really simple, and I hate to give away my secret but because you read this far, I'm giving you a cookie.
For Grinder levels (not super grinder mind you)....drum roll
Just use temporals and Meteors. (with score boost on the temporals)
Really, that's all you need.
Damn it, I knew I should have kept this one closer to my chest.
Acknowledgements / Resources
This guide would not have been possible without the contributions of users like Bathosfear and Quialiss who have done some research into key areas:
Link to discussion on score boost tower efficiency: Bathosfear