Strangeton House (2016)

From publisher blurb:

Proper etiquette, good manners, and what fork to use, are not typical skills a recursor needs, but to succeed in Strangeton House, a person needs to know all these things. After the murderous Ruk agent Alagh-Zahul has fled to Strangetong House after a failed attempt to infiltrate the Estate. A crack team has been sent there to find him and bring him to justice, but first they need to find out what identity in the recursion he is hiding behind.

This supplement is primarily a scenario, taking place in the opulent halls of Strangeton House. As servants, the player characters must use subterfuge and deduction to figure out who in the mansion have been replaced by Alagh-Zahul. This scenario contains special rules for the game master to have the investigation have a variable suspect. This means that the identity of Alagh-Zahul is not set at the beginning of the scenario, but is decided by how the player conduct their search. The supplement contains description of the recursion and its inhabitants, as well as five foci to be used with it.