Missing Dungeon Master by FTL. Any hope?

Besides this (indicating that GoG likely has everything ready and good to go, and all that's still needed is the thumbs up from the current rights holder) there's not much to hold your breath over/for, at least at this moment.

You can still vote for everything Dungeon Master over here, though.

Well, dungeon crawlers seem to be too niche as well, as desmontrated by Fall of the dungeon guardians.

By the way DG has a very good and interesting Post Mortem - https://www.managames.com/DungeonGuardians/#. Good read for people interested in these kind of things.

Were too niche, around November 2015(!), more likely.
Since then curation loosened up quite a bit, as demonstrated by the releases of Heroes of the Monkey Tavern, Legends of Amberland: The Forgotten Crown, The Quest, Operencia: The Stolen Sun, Conglomerate: 451 or StarCrawlers, to just name a few of the more recent retro-modern takes on the genre.

I know, it is just the same old completely useless "too niche" response gOg has....