Braid is a puzzle-platformer, drawn in a painterly style, where you can manipulate the flow of time in strange and unusual ways. From a house in the city, journey to a series of worlds and solve puzzles to rescue an abducted princess. In each world, you have a different power to affect the way time behaves, and it is time's strangeness that creates the puzzles.
Another true game with effort and thought as the backbone for the entire game. Does make your brain hurt trying to figure some puzzles out. I hope to see more games like this in the future.