I liked the achievements system, it's a an over kill for the jam. I also liked the different enemy types as well as the idea of different weapons although I don't know how to unlock them, the menus are very polished too.
The bullets spawn at the wrong place, they either spawn around the player or spawn at the right position but the player collider pushes them out of place which I think is the actual reason because they do collide with player, at one point the bullet spawned behind the player character and hit him in the butt pushing him like 1.5 meters away xD
If the bullet was functioning properly the game was going to be very good, but it's a something understandable given the time restrections.