I saw over at Slashdot Games where there was an article about an attempt to create a canon for gaming. Somewhat like a literary canon, which is a collection of works that are essential to read for anyone serious about literature. Everything from Tic Tac Toe to Halo is included though there are a few omissions. Head on over and let him know what you think or discuss it here.
It's not worth much except for the fun discussion. For instance, in "Computer Games - Adventure" he leaves off Day of the Tentacle, which is a cardinal sin. Feel free to try to put together our own list, I'll post it below if we get enough together.
*edit* If you think the comments system sucks you can try the forums post I created.