If the game is running at more than 59 FPS, there will be numerous physics bugs (hair and flappy clothing flying all over the place), cutscene audio will keep getting desynced, flame animations will be bugged (static) and some sounds during the game may not play at all. You have to somehow force the game to 59 FPS or lower for it to work correctly. That is however extremely difficult due to the stupid custom launcher the game uses and thus it ignores most of the common tools used to manipulate frame rate.

For anyone with high refresh rate G-Sync monitor, here is what I did with my 240 Hz display.

In nVidia control panel, first, disable G-Sync. Then go to "Change resolution" and pick a refresh rate that when divided by 2 will be the closest to but less than 60 (for me, it was 100). Then go to "Manage 3D settings", click "Program Settings", click "Add" and find the Warrior Within .exe (pop2.exe). Scroll down in the settings, find "Vertical sync" and set it to "Adaptive (half refresh rate). This transforms the 100 I picked into 50, meaning the game will run mostly fine.

This is the only method that worked for me. Any external program that is supposed to lock frame rate to a certain value or affect it in any way (including nVidia control panel) simply did nothing with this game. The game seems to run mostly okay with FPS below 60, the only issues I've encountered is that a cutscene had no audio for the last few sentences (might be an actual bug, not related to frame rate).

Hopefully, this might help somebody.