I have played an unnumbered amount of demos, there are good demos and there are bad demos. A demo should grab the player, and keep them entertained for a while. A good example of good demos are from spiderwebsoftware, they catch you into the story and at a point where you have gotten more questions than answers in the quests you have undertaken the *shareware demon* blocks your path at some place. Bad demos end before one gets into the story or the feel of the game, but at least one gets to try it before they buy it.