"It's one of those games with sufficient depth that you could play it for literal years and not get bored." That is the mark of a truly great game. I think there are a hand full that I come back to but there aren't many.

The two that draw me back the most are Goldeneye on the N64 and, oddly, Beavis and Butthead for the Sega Genesis. If you never played that one, it was a weirdly complex little game that, ironicly given who the the characters were, required a fair ammount of thought to get through.