Portal 2
Despite some gorgeous portal and gel effects, the Source engine is (still) showing its age in a few particular ways, like fire and explosions. The single-player story's pacing isn't perfect: each of the game's three acts start strong, but peter out as they proceed. And loading screens seem unduly long and frequent. But this is the worst I can say for Portal 2. It's a triumph that exceeds the brilliance of the first game, and - with new mechanics and a new co-op mode - greatly expands the concept's potential. I look forward to even more from the Portal franchise.
Better than: Portal
Not as good as: Braid, mechanically (though Portal is much funnier)
Stephen Merchant: congratulations on outperforming GLaDOS
Progress: Finished single-player and co-op