Unknown Armies was my 90s go-to for everything that I wasn’t running in Feng Shui.
While I found the system’s native setting more than compelling, there were more than enough innovations in the system that made it worth using in a number of games, particularly conspiratorial and supernatural games.
Making characters in Unknown Armies is quick and simple, useful enough to be used in all sorts of games. There’s very little you actually need access to the books for, and what’s there is available in the free downloadable preview on the Atlas site.
This keeps the barrier to entrance low, so that it’s easy to use as a pick-up game with players who don’t have the book. The skill system is very open to character customization and both encourages and rewards player creativity.
Where Unknown Armies really shined, however, was the mental stress system. Even now, seventeen years later, I’ve yet to see anything that handled the subject with half as much nuance. Even in games that I didn’t use the UA system in its entirety, I’d find myself importing the Madness System, or elements thereof.
While UA’s humanocentric cosmology directly stands in opposition to the Lovecraftian mythos, running Call of Cthulhu games in the UA system is not only possible, but to me preferable.
I look forward to the upcoming third edition of the system. From what little I’ve heard, it’s very promising.