Assassin's Creed 2

Party like it's 1499. Worth: $60
based on 360 retail

Italians tend to be very nurturing, until the stabbing begins.

This is the best single-player game I've ever played. Everything about the experience is so polished that even titles from game-making giants like Bungie and Epic pale in comparison to this masterpiece of interactive entertainment from Ubisoft.

Plusses: story, graphics, camera, control scheme, dialogue, voice acting, art direction, game world.
Minuses: none (although a Co-Op mode would have made this the best game of all time for eternity).