This game really piqued my interest! The idea is brilliant, and although I hate FPS games, I found myself trying this repeatedly! The alarm sound is a bit annoying, but the bgm is very nice! The fact that this game has been done by only one person is astonishing, well done!
If I really have to point some flaws out, I’d say: never put a HARD quit on the escape button, I have the bad habit of hitting it unconsciously whenever I’m testing out different approaches to a puzzle to reset the level as soon as possible.(and a think a lot of players do as well)
As a side note, I didn’t get past level 3, where the ricocheting bullet is almost unpredictable and most times it will bounce off the targets in a way that doesn’t even get to the third one (so, unless you know precisely where you are and in which way you shot in the previous attempt, you’re gonna be stuck there forever), where the game got a bit frustrating.
And I’d say that you should add the RUN function on every direction possible, not only on forward, because you’re tempted to look at the target while running to keep track of the bullet, and you can’t reach it if you don’t run straight.
Good job overall!