[Junkenstein]

Atmosphere coupled with intelligent gameplay is what really gets me. Pure distraction is good, but if the story, the deatils and the mood are done in the good way a game can get my heart much faster than any movie.

My favourite games managed to scare me (bioshock), make me feel like a cool mo-fo (arkham), laugh my ass off (All the sam and max games AND obviously monkey island) or at the peak made me feel like what i was doing mattered and the destiny of the characters was important to me (Mass Effect does that).

I think that games help escape from reality, but great games create a new, believable one around you. So, yeah, atmosphere+gameplay.

ADD: A good example that got way overlooked: Indigo Prophecy. Those damn controls took mor3e out of the game than a baseball bat but when you got used to them that game was as closed as living in a david lynch universe as you can get.

And Vampire The Masquerade - Bloodlines. Simple but cool as hell.