I bought this adventure to use it with our Aces High campaign (Chaosium Monograph) I am running with Basic RolePlaying. Was not familiar with the Pangenre RPG beforehand but after I got the adventure I saw that it was basically a d20 system similar to D&D3,5/Pathfinder.
I have read through the adventure but haven't had the chance to run it yet but it is planned to be used. It is very tied to different locations in the adventure and each location is seen as a mini-adventure. I like how simple and clear each location are organised together and the story seemed to fit very nicely together with our current weird west campaign.
Seeing as the system is d20 converting it to other systems shouldn't be to much work, as long as you have some sort of Old West sourcebook at hand you mostly just have to replace items and such with the ones written for the system you use.
The adventure is highly recommended for anyone who wants to run a supernatural horror mystery in the old west regardless of what system they use.
The only minus I can think of is that the adventure can feel a bit railroaded where you explore one location before moving on to the next one. But each location is very detailed and packed with atmosphere and they don't have to explored in a certain order. Each location is like different problem you have to solve to get a piece of the overall puzzle you need to piece together to solve the mystery. It is something I don't think people will dwell on.