I got a Google Alert pointing to a blog on game-based learning. I hadn't seen this blog before and I'm excited to start digging into it. The post was about an educational BBC game called Questionaut. It takes you through a series of worlds and the game part is trying to figure out how to get to the questions. Each world is themed, one being biology, another English, another about angles, etc. I haven't played it to the end yet, but I plan to go back and do this. For each question you get right, you get fuel in your hot air balloon to keep going up. I think you're chasing your girlfriend's hat, but I'm not 100% sure about that.
So again this boils down to a quiz game, but the graphics and how the questions tie into the game part are unique and fun.