Evergreen games
There are just some games that are immortal in my eyes. My criteria are two pronged: whether it's a great game, and whether the 2011 gamer can stomach its dated visuals. This sadly precludes a few early 3D classics like System Shock 2, Deus Ex, Ocarina of Time, etc. The chief assumption is that most people will agree with me that 8 and 16 bit graphics are easier on the eyes than the first generation of polygonal games.
It's a very personal list so there is an obvious bias, and this is by no means an authoritative list.
Still a work in progress, will add more to the list when more spring to mind.