Charles Kahler offers a primer on the “dungeon synth” genre:
Dungeon synth is an offshoot of the dark ambient genre of electronic music. Like dark ambient, dungeon synth compositions rely on droning synths and harmonies to create melancholic, sometimes foreboding atmospheres. However, dungeon synth is distinct in its goal of building soundscapes with a fantastical feel, and many tracks employ musical structures taken from folk or medieval-period music.
Related: My review of Thangorodrim’s Gil-Estel.