This reminds me of Weebl's Inverse Shoot Em Up. It's still a great game by its own right. I was amazed at how good the artwork was. I can recognize your style. The sounds are wonderful too. Everyone's done a variant of Mario.
It really was creative. You had a lot of different characters to play. I guess that makes sense within the context of the game. I can see why it's so popular. It's simply a smart, charming game.