Mass Effect 2
Super Mario Galaxy 2 is the best game of 2010, but it's not my favorite.
Mass Effect 2 takes the most important part of any BioWare game - the conversations - and puts it against the background of a fun and capable third-person shooter with lots of crazy superpowers. Isn't that great? I think that's pretty great.
Mass Effect 2 is better than its predecessor in every way that matters. Combat is fun, dialogue and characters are both an order of magnitude more engaging and believable, and the world in which you walk is much more complex and engrossing. Gone is the clunky (and terrible) inventory system. In many ways the things that have been cut away are a shock, and can even put some diehards off of the game, but Mass Effect 2 is expertly designed to communicate a very particular experience that BioWare wants you to have. That experience is wonderful.
The most important part of any RPG is its characters, and this game has the best cast of any WRPG since KotOR2. That's saying a lot.
Between us, the wife and I have put something like 300 hours into this game. It's the first game that either of us have ever bought DLC for. BY the end of its life cycle, I predict I will have spent three hundred thousand dollars on Mass Effect 2 downloadable missions. And it will have been worth every penny.
Now give me more bridge DLC, BioWare! Lair of the Shadow Broker was forever ago, and I'm jonesing!