So many people have problems with the game constantly crashing under Win 7/8/10/ xx.
I tried many suggested solution from compatibility settings to removing game music files. In the end, fix was super easy

Simply go to the options and set Full Screen to OFF (don't worry game will run in borderless mode now)
It removed all crashes for me being able to finish all campaigns with no crashes, worked on multiple PCs I tried it on, so I guess engine just do not like to run full screen.
Also if you happen to have problem with shadows turning pitch black try to set memory optimisation to off (I guess this depends on GPU you use)
Before I had crash every few minutes even with all supposed fixes.

(Elven Campaign final mission needs fix you can find in another guide and some achievements are wrongly written in game files that can be fixed also)