It's an interesting concept for sure, and matches the theme pretty nicely, but unfortunately I found this to be a somewhat broken experience. From the get-go, there are only five levels to play, but for some reason regardless of if you hit Play or pick level 0 from the level select, it will only cycle through four of them (1-4), with Play loading you into level 1 instead of level 0. As a result, I was at a loss for what to do initially because the brief and control list that occurs when you load up level 0 didn't appear for me.
I did eventually get a handle on the gameplay loop, and while it lasts it's an interesting time. With a little further exploration of this concept I could see a really fun and tricky game coming out of it. However, some major mechanics are apparently bugged or unclear. Regardless of if you complete or fail a level, you can hit the play button to move on to the next (where you'd expect a fail state to only allow a restart), and in level 4 the bullet counter is broken. It starts you with three bullets with which to kill four enemies, however when you land a shot on the third enemy it magically grants you a fourth bullet. Half the time, though, the level will slap a fail screen on you as you fire your final shot, making a hit on the final enemy pointless.
Outside of the bugs, I found a few things about the visual and collision side of things to be a little rough. There's a nice trajectory line on the player telling you which direction your bullet will travel, but it's far too short to reliably line up an angled shot. I also feel that the hitboxes on the bullets are a bit too large for the level designs on display here. It wouldn't be too bad normally I think, but when you slip an enemy into a single-tile alcove and have to land an angled shot past the corner of a wall, the larger hitbox on the bullets can really bite you.
Overall, as stated, the concept here isn't bad at all; it's just unfortunately marred by a few glaring bugs and the sadly short duration of the whole thing. With some expansion, fixes, and more interesting level layouts, I could see this really going somewhere!