Here a list of the top 20 best selling PC games in the US for the month of September 2008.

 1.Spore / EA Maxis / $50
 2.Warhammer Online: Age of Reckoning / EA Mythic / $49
 3.The Sims 2 Apartment Life Expansion Pack / EA Maxis / $30
 4.Warhammer Online: Age of Reckoning Collector's Edition / EA Mythic / $80
 5.Spore Galactic Edition / EA Maxis / $79
 6.World Of Warcraft: Battle Chest / Blizzard / $37
 7.Crysis Warhead / Crytek (Publisher: EA) / $29
 8.The Sims 2 Double Deluxe / EA Maxis / $30 
 9.World Of Warcraft / Blizzard / $20 
 10.Spore Creature Creator / EA Maxis / $10 
 11.World Of Warcraft: Burning Crusade / Blizzard / $28
 12.Civilization IV: Colonization / Firaxis / $29 
 13.Warcraft III Battle Chest / Blizzard / $39 
 14.Civilization IV / Firaxis / $27 
 15.The Sims 2 IKEA Home Stuff Expansion / EA Maxis / $20
 16.Diablo Battle Chest / Blizzard / $39 
 17.StarCraft Battle Chest / Blizzard / $20 
 18.Hot Wheels: Beat That / Activision / $15 
 19.Crysis / Crytek (Publisher: EA) / $38 
 20.S.T.A.L.K.E.R.: Clear Sky / GSC Game World / $39