Prince of Persia: Sands of Time
I've just finished playing PoP:SoT for the third time and I have to say it would earn its place in the top 5 games of the last decade. Okay, it's a bit short (a bit more than 6 hours the first time I played it, then 4h and 5h) but it looks good, plays awesome and is not yet another first person shooter designed with 42 shades of brown.
If you like games and don't have anything against platformers in particular, you owe so yourself to play this. It's also cheap (there's a pack with the trilogy for about 20 bucks if you feel like it, even if the latter two games are not as good) and will most likely run on your computer, even if you hardly ever upgrade it.
Hell, even Yahtzee liked it.