The oldest games the ones you can not find on the EB shelves, you can find them on or the piratebay
This isnt an encouragement to have you download the games illegaly. This is just because there isnt any other way to get them.
See, last time I went to buy thief 1 and 2, and EB games doesnt have them. But the guy whispered me to go to the Torrent sites and download them because none of the game selling stores have them.
Or go to Eidos.com and pay $10s to waste it on the old game.