Outer Self is a mission for Mega Maul, which is in turn a mall-based mission pack for FIST.
The PDF is 9 pages with a subdued, classy aesthetic. It fits the mall themeing perfectly, and the text is layed out in a way that sits nicely on the page and allows for a lot of good white space---although it does require a little magnification to read.
Contents-wise, Outer Self's hook is fun and pulpy, mixing witchcraft and bland corporate americana. A witch is stealing souls through photography, and running her business out of the liminal spaces in a fading mall.
It works better the less information the PCs have going in, and may be ideal for non-FIST-agent characters. The vibe is kind of Unknown Armies or Liminal Horror.
There are a few extremely deadly scenario elements, and one puzzle is necessary for progress, but the overall flow of play is slow and atmospheric. There's lots of "nothing is happening" rooms to build tension, and there's a great eerie feeling that pervades the scenario.
The scenario has an innovative map which bashes together photographs into a collage of explorable areas---it's super creative, and fits the visual style really well.
Overall, if you want a grounded, liminal, creepy adventure for FIST, this is a great pick.