From the publishers blurb:
A horror filled mansion-crawl compatible with MÖRK BORG role-playing game.
In The House of the Hollow, players will investigate a mysterious moonlit manor, home to a retired adventurer in the midst of a terrible transformation. Even before they encounter the moon-bound horrors lurking between the walls, navigating a decrepit house on the brink of collapse provides the players a significant challenge. A haunting revelation awaits travelers who enter the mansion, along with a powerful artifact ripe for the plucking.
The House of the Hollow is an independent production by Dylan Mangini and is not affiliated with Ockult Örtmästare Games or Stockholm Kartell. It is published under the MÖRK BORG Third Party License.
MÖRK BORG is copyright Ockult Örtmästare Games and Stockholm Kartell.