Nice game, I liked the increasing difficulty of the enemies and the upgrades. I thought the particle effects for the submarine looked cool too. One tip for the pixel art, try to keep a consistent base pixel size on everything in the scene. Like for example the base pixel size on the restaurant building is huge, while the door on the shop has a tiny base pixel size. Having an inconsistent pixel size makes the art style way less cohesive looking. Great job on this tho I had a fun time playing it.