With online
1 Starcraft
2 Warcraft 3
3 Wolfenstein Enemy Territory.
Without online
1 Dead or Alive 3
2 Civilization 4
3 Total War Rome
4 Timesplitters Future Perfect
5 Super Mario Bros 3
Note: I have probely played single player so much in Starcraft that it beats probely every other game just with singelplayer.
Think twice before helping a friend in need.