I would have never gotten Dead Rising without playing the demo, or PGR3, or Condemned, or many other games. Demos work. Onslaught could be an awesome game, but I'm not going to throw $10 at it unless I can try it first, same with just about any other WiiWare game. If you don't get a demo, then you basically have to go on reviews (after deciding if it looks like something you want, you don't just look at 9+ rated games and say "here's my money!"), and we all know where that will get you.