It all boils down to FUN.

MM just FUN gamer since NES days =), having fun with friends thats about it =)

To get away from my every day life
Relax
Fun
I can't sleep forever.... but I guess this is a decent alt...

entertainment really,its fun,relaxing,and stress relieving(well,some games)

wow u guys have some good reasons.

Compared to movies and/or music it's much more intersting(duration,variety and artistic component).
Additionally it includes the satisfaction factor which all the other entertaining media can't offer.

I enjoy the stories, the atmosphere, the evolving technology, and the gameplay. I like solving puzzles, competing with a friend, or winning against the AI.

All in all, it's simply the best form of entertainment there is.

Just to have fun. If I don't find something fun I don't play it.

Simply, for fun.
When socializing; Mario Kart, Mario Tennis, Rayman etc.
To test my brain and solve puzzles.
To relieve stress after a tough time, for ex: post-exam video game sprees.
To accomplish things I couldn't otherwise do in real life. For ex: exploring Tallon IV in a distant galaxy as a bounty hunter and taking down evil space pirates. I guess one can experience that in movies to a certain extent but they're not as immersive as a video game.
As stated before, for the memorable characters, worlds, music, stories.

I miss playing cooperatively in games such as DKC and DD.

A wise man once said video games are mental masturbation. This best applies to RPGs you are getting fake accomplishment to make your brain happy.