Quest for the Crown
Quest for the Crown, billed as "A roleplaying game parody", is sometimes called "the easiest game ever made". The premise is simple. The game takes place on a rather empty, large field, seen from above. Your character is a stick-figure that you can move with arrow keys - you move 1 square per key press. You have to reach the crown. (This takes about three seconds.) Once you reach the crown, you can sit back and relax, watching the credits.
Note that if you sit through the credits, the game will begin anew, although this time your movement distance with each keypress is increased by one. This makes it a bit more difficult to reach the crown.