1. Call of Duty 4
2. Bioshock.
3. Portal
4. Mass Effect5. Half Life: Episode 2
Do you disagree? Re-read the title and look up the concept of possessive words in the English language.

Play these games and you will understand. I seriously want Mass Effect for Windows, then I would buy it.

Are you a developer looking for a common theme? The single player experience.

-The Digital Kitty