Theres a few possibilities. 95's TIE FIGHTER was probably the best flight sim of all time, 14 years later no flight sim has drawn me in like it did. D00M continues to be awsome, with the controls now perfected now that they have been ported to the 360, I just didn't like the way my fingers had to stretch to make it work. Then there is the first command and conquer, having been one of the first relevant rts games and still a functional experience in this day and age. I can't decide between the three of them.