Since there are many different genres of video games and many different platforms, it is difficult to determine which is the greatest game of all time. However, I want to place EA Sports' NCAA Football 2005 into nomination for the greatest sports game of all time.
These are screen shots from the game. Notice and marvel at the details here. The different helmet styles (all of which can be altered for each player). The uniform details right down to the brand name. The exact stadium designs. And the realistic body positions of the players. It's astounding.
And the game play is equally detailed and realistic. Recievers look back at the quaterbacks and slow down at the appropriate part of their route. Running backs struggle to hear audibles in loud stadiums and sometimes run the wrong play as a result. Punishing hits by safeties will gradually give opposing recievers alligator arms as they reach for future passes. It's unbelievable.
I could go into more detail, but I won't bore you all with that here. But, if anyone would like further discussion, do not hesitate to email or comment.