KOTOR: I've never been hooked by a game like I was with this.  Oh wow.  This has got to have the best Star Wars story since Episode IV.  Choosing to go Light or Dark Side of the force was also very engaging.  I've tried replaying Dark Side, and just cannot do it.  That is how engaging the game is.  This is a must have.

KOTOR 2:  I rented this and decided not to buy.  It seemed much like the first, in fact, I think my issue is that it felt like I was just replaying the same game.