Call of Cthulhu - "The Sanatorium"

One of the first "Call of Cthulhu" scenarios I ran was "The Sanatorium"  from the compilation book "Mansions of Madness". In it's own way, it was the most important scenario I've run in terms of how it enhanced my GM style and built my confidence.

The scenario is about a private sanatorium on a small island off the coast of Massachusetts.The resident doctor is experimenting with hypnosis, still highly controversial in the 1920's setting.He invites a player character out so he can share his findings.Of course, it's not so straightforward.

One of the patients has been communicating with a creature from space while in deep hypnosis. The creature comes to the island and needs energy (in the form of human sacrifices) to free itself and return home. It can also possess the minds of humans. When the game starts, a male nurse has been possessed and has already started the sacrifices. The first victims are the hospital staff, and it's real fun when the players realize that the people welcoming them into the hospital are the patients!

One of the great things about this scenario is that all the characters encountered by the players at this point are patients, and hopelessly insane. The game becomes a challenge in that the players don't know who to trust, what information is real or imagined, all while being stalked by the crazed nurse. The real villain of the piece is so truly alien that they really won't figure it all out.

For me as a GM, this presented numerous challenges. The first was playing ten support characters.I had to keep track of them all and play them convincingly. All of the characters had important histories so it was a real test to make them come across as distinct people and interact with the players. The second challenge was the sheer size of the group...I had nine players! I'd never had a group that size before. The third challenge was the that group broke into three smaller parties, each exploring different parts of the ideal. So in all, a lot of moving parts where involved. That being said, the setting is a sandbox with borders....the players can't get off the island.

The important lesson that I learned was that I found it easier to run the game with multiple groups, timelines and threads. That was a surprise for me and it's certainly not the preference of every GM. I enjoyed that approach so much that I now encourage my Cthulhu groups to split up in most sessions, something that worked to great effect in the "Delta Green" game especially. It's a great scenario, especially if you enjoy confusing your players!