Limbo
I can't hail Limbo as a work of genius. It isn't as creative as VVVVVV, or as challenging as Super Meat Boy, or as elegant as Braid. The cold open makes the game's few controls a little confusing to figure out, and the monochrome graphics have the MadWorld issue of occasionally obscuring important information. That being said, it does very well for itself -- the environment is engrossing, the controls are solid, and the puzzles are genuinely clever.
What's most interesting about Limbo is the single-take design: setting aside its generous checkpoints, the entire game is one uninterrupted stream of level. It's a neat concept, and the puzzle design is to be commended for keeping the mostly-constant environment from becoming tedious.
Progress: On top of a giant rolling boulder