These would be my top three. Though I don't play that many of these games anymore...just some online.
Heard about that game from a ton of people in my WoW guild. Going to start playing it with them when it comes out. Not looking forward to paying WoW, Xbox and Aion monthly fees all at once though. :S
1. World of Warcraft 2. Call of Duty 4 3. Call of Duty 2 4. Counter Strike Source 5. Warcraft 3 6. Battlefield 2 7. Call of Duty World at War 8. Silkroad 9. Guild Wars 10. Wolfenstein: Enemy Territory According to Xfire
Xfire probably only accounts for the people who are registered through xfire. I'm guessing that's not an accurate number.
Xfire does only account for its registered member, but I just posted to give a rough estimate of what is being played out there. I would also include RuneScape on that list...
This game , although it only has a few hundred thousand people playing it is indeed deep and well worth a play