Mayfair Games Underground RPG softcover 1993: Gamemaster's Pack

System Mastery 235 – Ray Winninger's Underground

Underground GM Pack - Mayfair Games, Underground

Mendel Palace — Front cover (by Geof Darrow) and some interior

Battlelords of the 23rd Century (Military Sci-Fi RPG, 7th edition) by 23rd Century Productions, LLC - Galactic Underground 2 (6th Edition) - Gamefound

Base Raiders: From the Underground - Slang Design

A Place, Underground – L.F. OSR

Underground Waterfall, Michael Ghelfi

Mayfair Underground L.A. Campaign Sourcepack Streets Tell Stories RPG

d&d underground megadungeon map, Stable Diffusion

Communiques From the Psi Underground