Benchmark: StarCraft II
StarCraft II: Wings of Liberty is a sequel that improves on the original with an excellent campaign mode, incredible cut scenes and a multiplayer experience that never seems to grow old. Real-time-strategy games don't come much better than this.
Buying a graphics card solely for StarCraft II? NVIDIA appears to be the way to go, with even a stock-clocked GTX 560 Ti delivering acceptable performance at crazy-high resolutions.