Newsweek has an interview with Brian Allgeier, the creative director of Ratchet & Clank Future:  Tools of Destruction.  Allgeier gives five traits that make for really good video games.  According to Allgeier, good games:

  1. Begin with a bang
  2. Have a compelling main character
  3. Have a good pace of the progression
  4. Contain a Strategic Meta Game
  5. Fulfill a fantasy.

This is a a great read that illustrates what makes video games so engaging for players.