Solipskier is kind of a mix of the growing line drawing genre and the classic Line Rider game. A little headphone wearing skier (at least he wears headphones as long as he can keep them on) travels along a snow ridge that you actually draw with your finger as you play the game; he speeds up or slows down based on the slope that you trace out with your finger. The gameplay is simple to pick up, but it turns out to be pretty deep. You can draw quick ramps to make him jump, or you can draw sliding slopes that really send the guy moving along through all of the gates, tunnels, and jumps that get placed in your path.
There's a really great pick-up-and-play vibe to the title, and it's fun enough to keep you coming back again and again. If you don't believe me, give it a shot online right now for free. If you enjoy it enough to spend the money, you can grab a universal version on the App Store for just US $2.99.