When I run the installer it states; 'Game installation not found, please reinstall'. I've tried reinstall. Still doesn't find it.
Update: found the solution - don't install it via GOG Galaxy. Use a separate installer. The experimental patch doesn't seem to recognize a Galaxy-based installation of this game. Once I downloaded the non-Galaxy installer from the GOG site, the patch worked for me.
However, the patched version of the game won't boot for me. No error message or anything. Windows 10.
I had almost forgot about that. But thank you for the advice since it worked for me. All I had to do was to make sure to run the game as administrator, then it booted up just fine.
Hit me up if you want to try and get an online session going :)