@Jambalah

Thanks! The problem I seem to have is that it tries to load files that aren't in the right place. But (as usual) the manual isn't helpful here when I try to figure out what stuff I actually need installed and where. I installed the game on Windows and copyied the extracted version to MOS. Guess I'm doing it wrong again :)

Isn't Quake abandonware? If so, wouldn't it be a good idea to include the needed files with the launchers? Or at least the demo version?