Nice game! Are the blood spots objects or particles? It seems like they would have to be objects to interact and splatter on the surroundings, but that seems performance intensive, and your game runs really well! Congrats on a cool little experience
Thanks for the question! Each paintable pixel in the environment is actually its own object. I'm able to optimize it because it's all on a fixed grid, so lookup is really quick. I don't need to update the pixels outside of when they get colored in, and I only draw the pixels that are actually on screen, so it's all O(1). Paintable pixels on moving objects like platforms and thwomp are a bit more complicated, but follow the same general principal. It also helps that the art style leaves a lot of negative space, meaning there are fewer pixels to keep track of.