Great article that does a good job of explaining why people love of video games. In a nut shell the six moments that make video games worth it are:

1) When you truly feel power for the first time
2) When a piece of “Victory Music” plays
3) The first time you see an awe-inspiring enemy
4) The first time you see the universe running without you
5) Reaching the other end of an impossible level
6) Mastering the rhythm

Don’t know what those mean? Read the article. It’s on Cracked.com of all places.

Personally, I love discovering the trick to a level or challenge and the feeling, oh the glorious feeling, of godlike powers when you’re a high-level character smashing through bad guys. Sooooooo satisfying.