@Andrei Barsan thanks for the comments. I discovered during this jam that if I want to keep with the C++/SDL combo, I need to have some base code to manage the UI and the game states, because during the compo I never have the strength to work on this necessary but boring stuff. About the procedural fishes, in fact, they evolve but making the sprites is quite time consuming (that's something I plan to improve also) and didn't have the energy to make more than two.
@iximeow @juaxix it seems some people have problems with TinyOAL. juaxix the source is my full code repository, you should be able to build it from there.