i think a good challenge would be to take a character from an old 3D game that has a really low polygon count and remake it.
like how the FF7 characters went from being people with cubes for hands to super detailed people

or how bout, take an old toy and remake it so it can do the things you see it does on the box, like the old transformer toys or my little pony, so they'd be fit to be in something like Toy Story

or if a cartoon character were to appear in real life what would they look like?