Congo's Caper (1992)

Congo the monkey and his girl, Congette, were in the jungle minding their own business when a magic ruby dropped out of the sky and turned them both into half-humans. To make matters worse, the ruby also spawned a demon-kid who grabbed Congette and took off. Now you've got to hunt down the kid and find your girl, while adapting to your new form. You'll make your way through ghost towns, pirate ships, ninja castles, and the belly of a Tyrannosaurus on your search. There are 35 levels of side-scrolling action in all, and you'll have your hands full with tons of wild animals that will try to stand in your way. As you run, jump, swim, attack, and dive your way through the game, keep your eyes open for special gems that will give you special powers and open secret levels.