While it's true C2 is a 2d engine and therefore you can't create 3d games in it, you can however create pseudo-3d games, some of which look/work quite well.
It seems quite complicated though, at least from what I've read on the subject so far. I'd recommend you start with this tutorial, then google for some others.
I do however strongly suggest that you first try to create a couple of simple 2d games to at least get the grasp of things. Whatever you decide I wish you good luck.