The flash game QWOP is very challenging, using only 4 keys to try and make your character run.
Your a runner named QWOP. Your at the olympic games and are the only representative of your nation.
The concept of the game is to run at least 100 meters. Sounds simple enough right?
You use the key Q, W, O, and P to make QWOP move. Q and W control the thighs and O and P control the calves. Most of the time QWOP is falling backwards or landing straight on his face because the correct buttons weren't pushed. Making him run involves some kind of magical combination.
As you run farther in the game, you encounter hurdles. Go give QWOP a try and see how far you can go.