Too much to mention, but a couple of the top of my head:
Immersion: Someone has said it before, but being able to go off and do your own thing away from the narrative within games such as GTA, Fallout, Oblivion, Baldur's Gate, Just Cause, Battlefield.
Linking in to this is the 'emergent' gameplay/narrative, the cool moments that are completely unscriped that you remember for years to come. THe firsttime I shot down Plane all those eyars ago in Battlefield 1942 only to have it crash into the gunners seat I was in. I dived to saftey, but thought of it as a cool moment because it was not planned, it simply happened through a chain of random events.
Time investment/narrative scope: Een in games where story can be badly written in places, liek Fallout 3, the time investment with the characters trumps other mediums and usually aids to improve your commitment. Mass Effect 2 or either of the Baldur's Gate (PC) ganmes exemplify this clearly. Byt the time I had finished I genuinely care what happens to each character, and the world around them.
Interactivity, interactivity, interactivity: Half-Life 2 is one of my all time favourite games, and I don't think that is just for the narrative and aesthetics. It is the feel of the gameplay, the dynamic combat, the 'emergent' gameplay situations thanks to the grav gun, the aspect fo it that make it uniquely a video-game, and not a novel, movie, poem or short story.
benzooka said:
Actually: [http://en.wikipedia.org/wiki/Flow_(psychology)][footnote]the mental state of operation in which a person in an activity is fully immersed in a feeling of energized focus, full involvement, and success in the process of the activity. Proposed by Mihály Csíkszentmihályi, the positive psychology concept has been widely referenced across a variety of fields.[/footnote]
I so get this while playing Geometry Wars.