It's pretty nice, however it's a bit hard to distringuish between your projectiles and the ones shot by the enemy. Also, since this is a GBJam entry, the player shouldn't be allowed to use the mouse, maybe you could have used some D-pad + some kind of auto aiming?
It's also a bit hard to press space to shoot with the same hand used to move, maybe using the mouse button would have been a bit better?
Nice job btw!