I saw a news blurb the other day about the Mac demo of
Unreal Tournament 2004 (the Mac port is being handled by
MacSoft). After the 200mb download completed, the archive successfully expanded to a 400mb (!) disk image, which mounted successfully. Not finding a Read Me or an installer or anything, I just copied the game from the disk image to my Games partition and launched it. I saw the Unreal logo splash, and the game then quit without launching (and without an entry in any of the log files that I could see). I thought it perhaps needed to be on the boot partition, so I copied it there and tried again. Same result...
So I
posted a question to the Macworld Games forum (yes, I browse a number of forums in addition to ours!), and got a very quick and accurate answer from Peter Cohen, MacCentral's Senior Editor:
If you have an iSight, webcam or USB mic hooked up to your Mac, disconnect and try again.
Sure enough, I unplugged my iSight, and UT2004 Demo launched perfectly (and it plays quite nicely, though I haven't tried the online bit yet). This seems like good info for the missing Read Me file!