Thanks a lot for all the suggestions, tried them all, including the most promising one that was disabling all sound devices but my headphones in the Device Manager, but no change

. I'm starting to think the engine doesn't like my USB SoundBlaster Headphones.
Later I till download and try the free version of MBT to see how it goes.
Regarding playing without sounds... It's what I'm doing

the nostalgic "hex" experience makes the game too much fun to play even without them
