Fun game, I really enjoyed taking down the bosses. The shooting and shielding mechanic is fun to play around with and the lighting effects are pretty. The boss fights are really fun - they're pretty challenging, but they have patterns that you can learn and adapt to.
I'd increase the damage of your shots in general because it takes a while to kill the smaller enemies even with the close range shot. I'd also add in a teleportation pad when you beat a boss, since it's a little tedious to walk all the way back.
Great job on the game, it's a lot of fun.