The debate on here for which game is the greatest of all time seems to be a generational one. Younger players, who have grown up with fifth generation consoles and beyond haven't had the pleasure of playing earlier games. Iv'e been playing games for about 20 years now and true-fully there isn't an overall best game. Obviously.
If I have to pick one game however, then it must be Tetris. Tetris is without doubt one of the most playable and addictive games ever made. Its premise is so simple. Trust me, people will still be playing Tetris in 20 years time compared to some games out now.
Some games are criticized as being only graphics based. Well this is ridiculous, because it depends on what kind of game you want to make. Yes, some games are graphically good, but play wise they are bad, and some games look good and play good. But depending on what kind of game play you are trying to achieve can sometimes require sophisticated graphics.
Developers in the 1970's could only work with what technology was available to them at the time, so suggesting it was purely about the game play and nothing else to me is a fallacy. Hmm, having said that, the graphics at the time would've looked really impressive, I base the fallacy on people who argue to me that graphics were not important during those years.
Anyway, whiny rant over, some my other personal best games ever made are: Sonic the Hedgehog 2, Super Mario World 3, Castlevania, Silent Hill 2, Final Fantasy 6, 7, 10 (though 6 is the best), Desert Strike, C&C Red Alert, Mortal Kombat 3, Street Fighter 2, Tekken 3, Hogs of War...and a few hundred others. Geek is my name, geek is my game. ;)