To mark its 50th anniversary, the veteran publisher Chaosium has announced a partnership with The Game Theatre to create Cthulhu in a Castle, a weekend-long immersive roleplaying experience.
The event, described as a three-day Call of Cthulhu RPG vacation, will take place from January 23rd to 25th, 2026. The venue is the Cairnwood Estate, a Gilded Age mansion in Philadelphia, Pennsylvania, which will serve as the atmospheric backdrop for a weekend of cosmic horror.

This all-inclusive getaway is designed as a luxury experience for fans of the iconic horror TTRPG. The package includes a two-night hotel stay, six themed meals, and a professionally run Call of Cthulhu scenario within the mansion’s halls. The Game Theatre, which specialises in producing interactive and immersive adventures, will be hosting the event, having previously hosted gaming getaways in locations such as Glencairn Castle.
Tickets for the experience are available from a dedicated website, Cthulhuinacastle.com, and are expected to be extremely limited.
Investigators attending the weekend will have the chance to play through some of the most celebrated campaigns and scenarios ever published for Call of Cthulhu. The organisers have highlighted several epic adventures that could form the basis of the weekend’s mystery, including:
- Masks of Nyarlathotep: Often cited as one of the greatest roleplaying campaigns ever written, this globe-trotting adventure pits players against a world-ending cult.
- Horror on the Orient Express: A journey across Europe aboard the famous luxury train, where an ancient artefact and a series of murders lead to supernatural encounters.
- Mansions of Madness: A collection of classic scenarios focused on haunted estates, family curses, and psychological dread in New England.
- The Two-Headed Serpent: A high-octane pulp adventure involving a powerful corporation, shadow wars, and a reptilian threat to humanity.
- A Cold Fire Within: A campaign blending pulp action with psionic powers, lost civilisations, and a cult seeking to awaken a cosmic entity.
The Game Theatre originated as an Off-Broadway immersive theatre before expanding into promotional events for film studios and corporate team-building initiatives. Their focus remains on creating live, choice-driven adventures that bring players together for shared storytelling experiences.
The brave or unwise may also wish to celebrate Chaosium’s 50th anniversary here.