Great art and interface, and a beautifully simple idea at its heart. I like the variety of effects on weapons, but agree with other folks that the balance needs work. I appreciate just how hard it is to balance a game like this in such a short amount of time. It would also be really cool to introduce more mechanics that care about positioning, like having enemies block each other, etc.
I was able to upgrade a Redo Arrow to pretty insane levels for an easy win!