Love this game. A surprising amount of polish for a game jam game. I really like the art of the game as well. It also just plays really well. The inclusion of multiple pallets is very nice.
I have 2 suggestions for improvement. I think it would be nice to be able to shoot in 8 angles instead of just the 4. Just adds a little more control. Secondly, I would like to see a chance of an enemy dropping items if you kill them with a bomb. This could just be me, but I think using your bombs to blow up enemies instead of walls is really sick but probably a bad idea in the current game. But if you had a chance of a drop for doing so it might incentivize trying to use bombs on large groups of enemies. Just I thought.
Anyway, I enjoyed your game a lot and this will probably go into my collection of quick run-through games!