One of the BEST
I went in to Portal 2 with very high hopes, and walked out completely satisfied and never so excited to have played a game. Portal 2's single player is an amazing experience, forcing players to REALLY use their heads to figure out the brilliantly assembled "tests" while mixing in some humor (that's actually funny). In addition to that, we get an amazing co-op campaign (with the ability to end friendships) forcing players to think even more, with the addition of 2 more Portals. Easily the top candidate for Game of the Year