That is really helpful; thanks! One more question: do I need to have the same number of frames in the animation or will it adapt based on the pre-set frame size? (I have no intention of changing any sizes.)

Ball biters is a perfect example of the sort of thing I want to do; thanks for pointing it ...

I only have a little experience with coding, and none with Lua. I would like to make a mod that is purely cosmetic that would change the appearance of enemies as well as slightly modify existing sprites for worldgen. I don't want to change gameplay at all. How do I tell the game to use my sprites ...