Underground Defense Force -Sword and Sorcery and Swarm of Insects- android iOS-TapTap

The Underground: A Sam & Fuzzy RPG by Damocles Thread Development — Kickstarter

Underground - Mayfair Games, Underground

Canyon underground - RPG map by tomasreichmann

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

A Place, Underground – L.F. OSR

RPG: Deep Down In The Underground, A Labyrinth RPG Is In The Works - Bell of Lost Souls

My next game is a turn based RPG about a young child lost in an underground sewer system where strange fog is mutating the creatures and critters inhabiting the labyrinth : r/Unity2D

Base Raiders Fate RPG

Girl Underground — Zine Quest by Jesse Ross — Kickstarter

Review of Small World: Underground - RPGnet RPG Game Index