From MacPlay PR Director Jason Whong:
The following are problems we've been made aware of regarding the Sin demo (as well as the shipping version of Sin):
* Non - English Mac OS: Many international customers are reporting that they can't control the game. Our engineers are investigating the issue, and I'll report back to this forum when I learn more.
* 3DFX cards: Users of 3DFX cards are experiencing weird video-related bugs when attempting to run in 800x600 or higer.. The problem is with the 3DFX OpenGL renderer, as fara s we can tell. To fix the problem, run the game in 640x480 mode ONLY. Or, try a video card from another manufacturer, or using your Mac's built-in video capabilities.
Summary: If you're not using an English Mac OS system, save yourself a download until we come up with a fix. If you've got a 3DFX card, stick to 640x480.
Cheers.
Jason