Downloaded Intruder yesterday, played it for a while without issues. Tried to run it today, and about the only things I can see clearly are the sky and the menus; everything else is glitched out.
This with a Mac Pro 3,1 using an Apple ATI HD 5870 GPU.
It is worth mentioning that I've also spent the last couple days trying to get some Nvidia GPU drivers working, but that activity was just as much a factor yesterday as it was today. I have the same result today with the drivers installed and uninstalled.