Very fun! I ended up playing this more than I thought I would, was surprised there even was an ending. Overall, it's unusually polished for a jam game. I like the characters and music, too. I learned everything I needed by just playing the game. Letting the player keep the upgrades when restarting the game was a nice touch.
The only thing that bothered me that the attack squares didn't indicate in any way which enemy was attacking that square, it would have been nice not to rely on memory and attention.