What makes a great game?

It depends on the genre, but I'll list what I can:

Action: Fast paced action that never lets up

RPG: A grand story and inticing gameplay

Strategy: Having to actually come up with strategies and know how to apply them

Puzzle: Addictiveness. That's it.

Fighting:  Challenging gameplay that's easy to get into

Racing: Upgrading cars and challenging opponents

Sports games: I don't know, seeing the crack sweat on this season's John Madden Pic? :? 

unlike most people the anwser is not graphics thats only a part of it.

what makes a game great is the plot the gameplay the graphics the enjoyment level and what makes a game great in your own mind and what makes a game great to eveyrone else are two totally different things.so don't go around saying this game is great if everybody disagrees keep it to yourself! GRAPHICS AREN'T EVERYTHING!!!

Better graphics

More nudity

Less talking

Chainsaws 

The words "Metal Gear" in the title lol

Generally: a good amount of stuff to do; balance between too hard and too easy; either advanced or well used graphics; longativity; originality

    What truly makes a great game for me is when it seems to transcend the player/system interface.  When I can play a game and feel like it's an extension of my fingers where I don't even need to think about what I'm doing and am fully immersed......that to me makes a game incredible.

It's almost like the game is "molding" itself to you when you play it.  Few games have ever accomplished this, but The Prince of Persia: The Sands of Time is one that pops immediately to mind.

This aspect is what makes a game great and is more important than all others.

So I suppose it's playability.  That is the core of what makes a game great.  Everything else is just building off of that foundation.

In a singleplayer game, I know the game is going to suck. Events are scripted. Bots are stupid. Levels are the same no matter how many times you play it. That's why the only redeeming factor is the story. But 9/10 it's the same SAVE THE WORLD bs that I'm sick of.

In a multiplayer game, I want a game where I'm facing people of my own skill level. Playing against a total noob or a pro just isn't going to end well.

I hate RPGs, reflex games are... eh, but my main forte is strategy. 

The only thing that a game needs to be good is to be fun. Now the question would be what makes a fun game? but that is a hard question about which books could be written if someone had the necessary knowledge.