Some of my favorite music to play while gaming is the first, self-titled LP by German Psych/Krautrock band German Oak. Their subterranean, grim yet funky jams are the perfect soundtrack to a Richard Corben/Ralph Bakshi animated rendition of the stories of Clark Ashton Smith.
"...an underground rock band consisting of five hippies from Dusseldorf who recorded tracks in a WW2 bunker, trying to capture the chaos, terror and bewilderment of war, air-raids, invasion and occupation. Neither fascists or Nazi-sympathisers, German Oak turned their anger on their parents generation for letting the National Socialist Party get to power. With a sinister, militaristic cover and 'off-putting song' titles, their first album sold less than 10 copies..."