Favorite Single Player:
This is a tough one. I would have to give this one to Bioshock. I beat the whole thing only one time and in basically one sitting. It was such an experience that was haunting and enlightening.
Runner-Up: Star Wars Knights of the Old Republic 1
Another toughy, but it's easier than single player. I'm actually going to differ from what I though earlier today and say World of Warcraft. That game has sucked me in and kept me there for the longest amount of time and offers such an in-depth system of player interaction that I have to give it to it.
Runner-Up: Team Fortress 2
- World of Warcraft
- Rock Band