Cool game - although I agree with others it was a little confusing at the start. Once I understood it I thought the strategy would be just to hold down the fire button - but there was a cool down after a while. It might have been helpful to show that though, cause sometimes I was confused as to why I couldn't shoot.
Visually, everything looks really cohesive. The art is simple yet great, the screenshake is a nice touch but not too much, same for the particle effects. Sound gets a little repetitive, but I find it rare when it doesn't in a jam game. Great effort for a first game!