In the border between Idaho and Oregon, in the obscurity of darkness and wilderness, lies a bunker with a door to another world.  The only hint to its existence in the Bortle 1-scale wilderness was a road for waste removal and occasional deliveries.  But no trucks have traveled there in months.  It is excruciatingly quiet—no birds, no bugs, nothing.  Inside, only emergency lights flash.  15 meters of concrete failed to contain something that should not be here on Earth…

This bunker is designed for five men, which could either be your players, or the occupants (dead or alive) of the bunker that the players find.  You might use it as an XCOM-style base of operations as your players enjoy dimension-hopping adventures, or as a point of interest for a Backrooms or Pulp Cthulhu or other sci-fi RPG.  It was built as an entrance for my Aberration Dungeon tileset but you might use it for any world, such as GM-Matt’s many extraplanar locales.  This “dungeon” is designed with 3 primary entrances for the players—a stairwell that connects from the entry, the elevator shaft, or the elevator itself.  The elevator is a realistic design with an access shaft, motor, and counterweight, so perhaps your players might enjoy a “physics puzzle” instead of a dice check, in that way.  Whatever your system is, each of the 3 entrances should be set as a reasonably high difficulty so that players are encouraged to poke around before breaking into the bottom floor.

The bottom floor itself contains a set of lockers with 4 hazard suits, some weapons, and an airlock into the portal chamber.  The portal chamber includes some samples that the bunker’s occupants have already extracted from the alien world, and some big red buttons for the players to mess around with.  I also placed security cameras in multiple locations, so at the computer in the portal room, you might provide players with a narrative of what happened with the previous occupants.  Above the bottom floor is a bunk room with a kitchenette, and a bathroom with showers for decontamination.