I've wrote storyline for my variant which explain everything (existence of DnD monsters, mixing of objects from different Ages, etc): https://tangaria.com/news/world-lore/
It's main idea (rifts and dimensions) will fit in any *band actually, especially to multiplayer variant :)
Storyline for *bands (including MAngband)
Storyline for *bands (including MAngband)
youtube.com/GlazGame — streams in English ⍽⍽⍽⍽⍽⍽ youtube.com/StreamGuild — streams in Russian