Ruin Explorer
Legend
Yes that's certainly part of it. There's a bit of nuclear war/nuclear reactor stuff, too, and technically spoilers (I'm sorry I'm not spoiler-blocking 34-year-old GM info in a thread about the book lol), but the guy they regard as their god, Rafiel, looks exactly like a stereotype of "1940s nuclear physicist" (in a handsome kind of way), right down to being human, and... that is exactly what he is - a human nuclear physicist from a long time ago who someone managed to transcend physical being (shades of Dr Manhattan - Watchmen came out a few years before GAZ13 - 1987 vs 1990 - but I think the "nuclear physicist who has transcended physical being" concept goes back even further).so let me get this straight, shadow elves are just elves from a fallout vault more or less?
There's also a lot of usual "underground living" stuff - i.e. glowing crystals, special magic, farming fungi, etc. etc. and they are unusual because they have an Elf Cleric equivalent (Shaman) as well as the usual Fighter/Mage-style class.
My brother and I weren't big Mystara fans generally, because the whole "totally unrelated cultures with no exchange whatsoever despite being adjacent to each other and not isolationist" vibe of the setting didn't work for us, but we did love GAZ 13.