Great use of the theme, and pretty ambitious project!
There is much potential here- I liked the procedurally generated levels, the idea behind the enemies, and the fact, that you really get to use (almost) everything.
I think that the game could use some more playtesting, and polish. For some reason I had two magic guns (one with 0 ammo). I think I'd prefer fot the magic gun to have a long cooldown instead of limited ammo, because you just get stuck, if you aren't presice with it.