Amazing game! The controls are as good as you could possibly expect from a jam game (plays great with a gamepad!), the gameplay is fun, challenging, mostly balanced, the art is both functional and beautiful. The writing is great, it's rapid and doesn't bother with meaningless details (even though it might be trying too hard to get out of the player's way). It's also easy to skip. Even the music does the job, although it's from an asset pack. Having no checkpoints was frustrating, but it did mean I had fully mastered the game by the time I beat the final boss. There's the overview, now I feel like mentioning some details. Spoilers ahead.
Abilities
As I said, this game is hard (and I love hard games). Using all your abilities is essential for beating the game. You have basic movement like walking, dodging and running. You have a melee attack, which works in all directions, but could be more fun with a little automatic targeting help (not full assistance, more like a soft lockon). You also have a ranged attack, which lets you slow time to aim. You also can pick up heavier ammo, which gets used before your regular shots so if you want to stock up you can't use ranged at all. Which is a nice dynamic. Though it might not seem like it at first, the slow motion you get from dodging an attack the last second is by far the most important ability. It lets you quickly kill even armored enemies, and lets you dodge out of the most dangerous situations.
Enemies
There is a nice selection of enemies. Not a huge amount, but they are all unique, which is a good choice. For the most part you can tell them apart by color. The only exception is the ranged shooters and the bombers, which are both grey. My least favorite enemy is the green enemy. Its attacks are too fast, so you have to learn to predict them if you want to dodge them. You also have to chase them around the arena. That's not to say I hated them, they are just always my first priority to get rid of. The grey ranged enemies are good to save for last, since you can get the slow motion effect easily from them.
The Boss
The boss fight is incredibly well done. I could dodge every attack, which is a sign of good game design. At the same time, the fight is very fast paced and you can get killed very quickly if you slip up. Around 50% HP, the boss spawns some minions, which change the pace of battle. To me, this duel is everything a boss battle should be.
Game feedback
This is what I feel is the weakness of the gameplay. With high difficulty and no checkpoints, this game begs to be mastered. But with unclear feedback, learning the ins and outs of the game becomes unnecessarily difficult. For example, it's not always obvious that you've been hit by an enemy. There are so many other effects and things to pay attention to, that the wimpy flash is hard to notice. Things like you taking a hit or an enemy winding up an attack need to have higher visual and aural priority.
Overall
A well made game with crushing difficulty. If there were checkpoints, I would probably go around recommending this game to people. Right now seeing the end takes so much determination, so it would be nice if you made the game more accessible.