After looking through the data, I need to make my annual plug for the following games:
Deus Ex at #225 (my #2) - if you love action RPGs, emergent gameplay, and the ability to play the game your way, you have to play this game
Tomb Raider (1996) at #247 (my #27) - trust me; this early 3D action-adventure game holds up even today
Psychonauts at #332 (my #28) - if you fancy 3D platform-adventure games in the Mario/Banjo mold, give this ingenious game a try
The top 20 is something Personally, I think Super Mario and The Legend of Zelda are the two best video game series of all time, but I'd love to see more diversity in the front half of the list. I suppose it's a product of so many individual Mario and Zelda titles being so beloved.
I think the only game that only I ranked was Beyond Good & Evil. I'm holding down the fort, @Mnementh :)