I love mashups. Whether in music, film, or elsewhere, a good mashup takes the best parts of its two (or more) constituent works and makes them even better by putting them in a different context. Mashups work just as well in RPGs. Shadowrun, a mashup of fantasy and cyberpunk, has been drawing players in for 35 years. Rifts, arguably an attempt to mash up everything the designer could think of, has created many more fond memories than its ruleset would suggest. For today, though, I’m going to dig into a more literal mashup, a setting where two worlds collide: an RPGnet thought experiment and proto-setting called The Long Stair.

As recorded in a long thread started over fifteen years ago, The Long Stair was intended to be a combination of ‘spec ops dungeon crawls’, Cold War shenanigans, and a little sprinkling of cosmic horror as D&D creatures made it ‘up the stair’ into the real world. While it’s certainly not the only way to do it, this setting illustrates a very well realized example of worldbuilding from a thought experiment, in this case the idea of sending modern-day operatives into a D&D dungeon.