Gameplay, Story, Graphics, and Sound are too broad and easy to claim as the most important part of a game.  So what do you as a gamer specifically think is the most important part?

For me it would be the pacing of a game.  In other words, the rate of speed that things happen and when they happen in the game.  Like right before a boss fight an intense storyline would lead up to it and give it more meaning instead of just fighting a boss and zooming right past a level, or getting items or abilities at an appropriate time to balance the game.

axumblade is someone I agree with.

...Does it effect your life.
Like froarora Mario,you play it and maybe smile now and then.But it has no soul on it anymore.
Then we have epic games like Final Fantasys and Metal Gears that really make you impact...Cry,smile,fantasise,smile,something....

Also,at Cod 4,when nuke strikes,thats about one of most coolest thing that he survives from that,but then dies...

Also soundtrack is good thing to have,like in FF and Mgs.

Looks like axumblade beat me to it.