The game launches on my secondary monitor, for no reason. In itself this wouldn't be that much of a problem, but on the map, the mouse slips out of the second monitor onto the first, and I cannot do anything, because I get alt-tabbed onto the desktop as soon as I try to press anything.

Same here :-\

I got this reply from GOG, which resolved it for me, although not ideally:

«I am afraid that this is an older title that simply has not been designed with a multiple monitor setup in mind.

Please disable all but the primary one before attempting to launch the game.
To do this, use the WindowsKey+P combination and use "Computer only". If this doesn't work, you need to disable the monitors in the graphics device Control Panel (right-click an empty section of your desktop to access it).

Looking forward to hearing from you and, hopefully, to your good news.»