World of Goo is a puzzle game based around "goo balls." Players connect the balls one after another to form elaborate, often unstable structures, all with the goal of reaching each level's exit point. The indie game stands out for its remarkable level of presentation and approachable, but puzzling gameplay. World of Goo was one of last year's most critically acclaimed titles, eventually winning several awards, including the Interactive Arts & Sciences' award for "Outstanding Achievement in Game Design."

If you haven't played it, now is the time. Get gooing.