A post by JoWooD Entertainment to their forum says that the Painkiller: Resurrection demo released yesterday was an older version of the demo, which was not intended for release (which may explain its release in .iso format). Word is: "We are very happy about the feedback concerning the demo but we are also sorry because we accidently released an old demo version. We really feel sorry for that. Next week we will release a demo version in the actual quality of the final game. So stay tuned and sorry for the inconvenience." Thanks Ant and Eggtooth.