Cool game. It's a pretty simple idea, but you executed it very well which is what matters.
It's a very visually appealing game with the simple, but beautiful neon, geometry wars art style. The extra effects on your shots, the background, spawning, completing the level, dying, etc, etc. really give the game a lot of polish and make it feel complete.
Your level design for the most part was very interesting. The levels all felt like they had something new to offer, not just a rehash of a previous level. The levels played a bit like puzzles in the way that you had to figure out what to do before you even attempted to do it. This game reminded me a bit of the game N(or N+ or N++) with the puzzle-like level design and especially the enemy that shoots at you. The levels did tend towards being a tad too difficult and like they had too much going on in them, leading them to fell unfocused. Take level 17 (I think)(see below) for example which I have dubbed "Gauntlet". The main obstacle of the level is to get through the gauntlet so to speak. You need to drop down, run away from the enemy shooting you, but then at the last moment, propel yourself upwards to avoid the spikes and then make it to the exit. Except the exit is locked. So then you just have to go push the pink block from the right onto the button to the left and fly back to the exit (not even needing to take the gauntlet a second time). I think the pink block on the switch is largely unnecessary here. Sure, maybe once in a while a player pushed the block to the right, then realizes the box is stuck and then needs to restart. Or a player is so good, they can push the block to the right, get under it before it hits the ground, catch it, and push it up and back over the ledge to the left side, but I think that is a little far-fetched.
Level 17 (I think)
There are some design choice you made I'm not sure I understand. When I first came to the level with the 6 stacked pink crates I thought "Aha! Those crates are pink, my bullets are pink, I must have to fly up to them, then spin around mid-air, and shoot them to destroy them" but then I shot them and my shots barely moved them. That was ok, at least it moved them a bit. Then I flew into them with my character. And they moved 10x as much as when shooting them. So I said whatever and continued on. Then I came to the point with the yellow obstacles and my bullets DID destroy them. So basically I'm confused as to why my bullets are pink and there are pink obstacles, but they don't interact very much, but then there are yellow obstacles that my shots do interact with. Then also lump in the yellow spikes that aren't destroyed by bullets and the yellow enemy shots that ARE destroyed by bullets (which I too only realized by your comment to Monstr down below). I think having things that can be destroyed by your bullets all be pink (enemy shots would then probably need to be a slightly different shape to differentiate from your shots) and things that can't be destroyed by you all be yellow, it would make the game more intuitive to the player. Maybe you had your own reasons for the colours, this is just what went through my head when I was playing.
Sorry about being super wordy about my critiques, I wish I could make them more concise. All in all, I think your game was well done and felt like a pretty complete game (a lot more so than most game jam games).