Bryant over at Population: One posts about and interesting web game called Pyroto Mountain. It's mostly a trivia game, but there are some interesting little twists. One of which is you don't have all the rules when you start out. You're also required to interact with the other people playing the game through bulletin board posts.

As you gain more power you can climb higher up the mountain's 512 levels. But there are some other catches you'll find along the way. I've only been playing for a few hours, but so far it's pretty fun. I think I'm hooked too.