I am now on Game 7 but since that time I added Enemy Within, so it probably would be a little longer to do since all the patches and everything, but it can be done if deleting all of Steam and whatever it leaves over on your computer. Re-installed Steam Client and the game and the game started over on Game 1. When I re-did Enemy Unknown, I deleted the game (which really does not just takes it out of showing it on the drive, and deleted Steam Client and anything left over.
