Spyro the Dragon. I could never catch Gnasty Gnork to make him drop the other key. Had to wait until I not only had a child but until he got old enough to hold a controller. He must've been a good six years old when he got that key for me. Spyro wasn't quite the same after that.

There was another game (name I have misplaced!) with an ice level. Not a hope in hell. No it wasn't Chip's Challenge, I finished that!