SirHandsome: Dark Omen has problems running on modern OS. There is a fan site where they patched the original install to work on Win 7 but if I remember right even that has a few strange work arounds.
Your best bet is to buy a PS3 and the original PS1 port of the game.
SorrowSeer: psx version of Dark Omen is seriously cutted compare to original (pc) version.
Indeed, additionally controls are horrible and it looks like horsesh** compared to the D3D-beauty on the pc.
The game in its original form needs some work to run properly. I'm running DO on Win10 at the moment without any problems. There was once an illegal installer version floating around the web that did all the work. I'm not quite sure where I got it from. The only thing I always had problems with the game was the 3D-acceleration: On some graphic cards it works, on others it doesn't. Generally NVidia-cards seem to work much better, I had no luck with Ati-cards however. In software-mode it worked everytime I tried it, but is far away from the original beauty (especially noticable with the ugly banding in dark regions, due to unsupported 16-bit dithering on modern graphic cards).
If GOG manages to solve these issues and present the game as I can remember it from back in the days I'll gladly pay some of my hard earned coppers for it.