I will flesh out this review over time.

HOWEVER, PLEASE KEEP IN MIND:

You get what you pay for.

This game is CHEAP for a reason...

PROS:
-Innovative Difficulty System. This was neat. I enjoyed watching my difficulty level go up as I played the game.
-Several weapon choices to choose from. This was also quite neat.
-Fresh spawns of enemies frequently. This keeps me busy.

CONS:
-This isn't flashy at all. This is simple, elementary gameplay.
-There is... Quite honestly... Only one type of enemy.
-The game is beaten extraordinarily fast. There is little to no replay value.
-Several things are NOT explained in the game. This is bad.
-The music you hear in the trailer? Yeah... That's not in the game.

Essentially, you are a... Human? With an arsenal of weaponry. You're trying to kill the Alien Race. This is nothing special. Nothing spectacular. There is no such thing as a "Story" in this game. Period.

The weaponry is basic and nearly everything is the same. It's nothing to gawk over. Different fire rates... Different power levels... But essentially the same weapon.

This game will be beaten once, then probably never played again, unless you thoroughly enjoy this type of game.

Overall.... 6-7/10, but ONLY for the price it is listed at. I can probably milk an hour, hour and half out of this game. I highly doubt I will get much more.

EDIT: This game is currently experiencing crashes. I'll update my review at a later time when these crashes are no longer persistent. Unfortunately, I will need to change my "Recommend" to a "Negative" Due to this aspect hindering gameplay.

Beat it in 20 minutes. The "campaign" is about 10 levels. But you can't even do the campaign until you play "battle" mode a dozen times, which is the game's way of making sure you know the game before you take on the campaign. Not worth even on sale for $3.50. Maybe 0.99 cents it would be worth.
Koya Rift has a a bug where everytime you access the weapon color details page it crashes when you exit it.

The only thing that would extend this game would be to have more upgrades for your character and with that an endless survival mode. Other than that, the maps may be random but certainly not "procedurally generated" as the trailer boasts.

Maybe for a dollar. There just isnt a lot of content. I didnt actually mind the gameplay so much, but it is very very basic. You cant play the campaign from the start, it forces you to play a number of random battles first. I found that annoying.

My overview and opinions on this game are in my Steam Backlog series (I wish there was a neutral options but I found more downsides than ups, though I really did like the way difficulty was implemented):

https://www.youtube.com/watch?v=UvzkfPER4FE

-Way too easy, way too short. I completed everything the game had to offer in 70 minutes.

-There wasn't any real challenge to it.


+Gun visuals are nice
+worse ways to spend 3 dollars and 1 hour, I suppose.

i think i would enjoy this game more if it didnt crash all of the time

Basically a flash game. With a bit more polish and variety this might be worth a poo.

Slow starter, pixilated, and gets very boring very quickly. Simple rules; get farther, get more points with no additional add ons or additional rewards available. Very poor.

Koya Rift is a 2D Action Platformer, with a big emphasis on random generation of both maps and weapons, as well as a scaling difficulty.

While it has its heart on the right place, and does everything it says (on paper), its methods don't prove as effective.
The main problem here is that all the random generation alters stats and numbers, but everything feels the same.

Presentation
For the game's scope, I think it looks and sounds pretty good! Especially since it was made by only one person, and a musician. It won't blow your mind, but it's really solid.

It's simple looking, but each weapon has a different color, creating some pretty great light effects. The fact that it's not low-res helps it quite a lot to stand out as well.
The enemy design is my favourite part. While there's effectively only one design (with some changes between each type), it gives the game a lot of personality.

The player character, allies and turrets also look pretty cool. It's more modern that you would expect from an indie game.

The only problem with it is that, when there are many enemies and allies close to you, all shooting at each other at once, the game gets a bit frame-y, and the explosion obfuscate everything else. Your best bet is to just stand back, otherwise you'll be hit by a lot of hidden bullets.

Everything is also color-coded. From the enemies to the weapons, its color will determine its effects, like piercing, explosive-damage, life-steal, etc. This leads to the next aspect: interface.

The interface is simple and functional, I like it. However, the loading screens and the way it teaches you these mechanics is a bit of a problem, to me.

During the loading screens, you're presented with leaflet-esque presentations with the colors, story or enemies explained. While they're pretty neat, visually, it's still a screen with paragraphs of text, which is definitely not ideal to teach a game's mechanics.
Regardless, I don't think it plays a huge part in actually playing it, and you'll learn what you need in the first battles.

The sound-effects were pretty standard, nothing noteworthy. Still, whenever an enemy died or you destroyed a crystal, a sound played, giving you good feedback.
The music wasn't bad at all, although it was a bit... generic, I guess. The musicians is clearly talented, so it would have been nice to have something a bit more unique. Also, it doesn't loop very well, and it's pretty short, so you're very likely to hear the wrong looping every level.


Structure & Mechanics' Overview
There are two modes: Battle and Campaign. The campaign is basically progressively more difficult battles, with a progression system added to it. The battles lose a lot for not having any progression. They take 5-10 minutes at most, so it's not like a Binding of Isaac, where there's progression in each battle. Not at all. You can pick a few power-ups, buy a few droids, but it's almost meaningless, since they're so short.

However, these battles serve two purposes: as a tutorial, and difficulty measurement. Before you unlock the campaign, you'll have to play a few battles, first. This is basically to teach you the general mechanics before jumping into it. Aside from that, it's seeing how well you do, and deciding the campaign's starting difficulty.

I've done more battles than necessary, and finished the campaign 2 or 3 times, so you can see that it's very short.

Let's now talk about the weapons. As I've mentioned, there are specialized effects that are color coded. These will basically determine what weapons you'll want to carry with you, for the different situations. Usually, I took one with slowing, one with life-steal, and one with explosive-damage. But there are some other choices, that I won't detail.
Aside from these effects, and during the campaign, there are also attributes.

These include rate of fire, size, accuracy, and homing. There are 4 or 5 ranks to each, and the price for the upgrades increase the more you buy.

You'll also be able to pick weapons in power-up form, that you can switch between, and also upgrade. These have a decent variety, because of the stats and effects combinations. However, the game has a tendency to overwhelm you with these. By the end, you can have 10+ weapons that you have no use for (1).

The enemies also have different weapons, with these characteristics. Also, some are faster, some are more deadly, tankier, etc. Visually, they have a similar base design (with differences in size and form), but you can generally distinguish well between them.


In each battle, you start at your base, and then have to go underground to destroy every crystal and enemy. Your base, if not under attack, will heal you, and restore your energy. Energy depletes when you shoot.
You can also buy Droids and Turrets, in the base. These rank up, becoming more powerful as they kill enemies. Turrets are stationary, and just for base defense. Droids can go with you, or stay defending the base.

Droids are basic units that will follow you around and shoot everything they see. They'll also be in front of your character, tanking the damage.

If your character dies, you'll have to control a droid, and go underground to the place you died, and ressurect. You'll ressurect with as much energy and HP as you had (or, well, very little). This plays an important part about difficulty, which I'll talk about later (2).

There's a bit issue with these droids, which is their path-finding. The maps are randomly generated in squares, with lots of intersections. Your allies VERY easily get stuck in those, and you'll have to manually do a dance to get them out. If you don't, they'll simply be reset back to base. This is really annoying. In some levels, as you'll have to constantly go back and forth...

The power-ups are quite varied to. They include shields (for you or your minions), helper weapons, ranks, energy, etc. There's one particular power-up that's awesome: it's gives you the ability to basically phase through the walls, slowly losing HP. This lets you go around enemies, escape more easily, etc., giving you more strategical choice. Unfortunately, there aren't that many situations where you can use it appropriately, and it's the only power-up with a cool ability.

I think this is enough. Now, to talk about the 2 major points about this game, for me.

1.Weapons
They are indeed randomly generated, but there's one big problem: they all feel exactly the same. There isn't any mechanical quirk to any of the weapons, and every element is merely numerical. Faster rate, more damage, spread shot, etc.
It's unfortunate. However, if they actually felt different (in a different game, I guess) it would be much more interesting. Perhaps an overheating laser, or a manually reloaded Shotgun, etc. Then, each type of weapon could have its own stats and progression.
Just my 2 cents. In the end, they all feel the same weapon, in this game, which defeats the point of random generation, a bit.

2. Difficulty
While the procedural generation does what it promises, the game is still far too easy. I didn't have any issues, with the exception of the last campaign level, and because of a very specific reason. It's basically a big room with lots of huge enemies. If you die, you'll fall to the bottom. And then, getting yourself out is a pain in the ass, because you're bombarded from every direction...
Aside from that, it's too easy, and you just need to be careful, with certain enemies.

Conclusion
This review may sound overly negative, but being critical doesn't mean I didn't enjoy the game! It's actually pretty good, for what it is. Sure, it's limited and byte-sized, but it's a fun experiment, for a couple of hours. Recommended on a sale!

Game takes 30 min to beat. Forced to play boring battles before starting campaign, how stupid, and way too many battles. The campaign has basically no story. It is the same as the battles. You literally go below the surface and destroy cystals that spawn guys, which all look the same but are apparently different. All the guns basically do the same thing except for rate of fire and damage, but that is hard to tell. Game crashes if you try to read more about guns. Every level plays the exact same, as you go below and destroy cystals, then come back up to get reinforcements and then destroy everything. game is boring and not that fun. you can make a few upgrades but they are meh. 5/10.