Mark of Cthulhu: An Escape Room Adventure, by Gauthier Wendling

The door is locked. Cthulhu is awake. Better start looking for clues.

Mark of Cthulhu is a book-length escape room adventure by Gauthier Wendling, inspired by the cosmic horror of H.P. Lovecraft and one of his best-known creations: Cthulhu.

Cthulhu has awakened, and getting out won’t be as simple as finding the key. You’ll need to explore rooms, search for clues, solve puzzles, and piece together what you discover as you work your way through a series of mysterious traps.

Inspired by real-life escape rooms, the book turns observation and deduction into the heart of the adventure. As you explore, you’ll encounter pages designed as an in-world notebook, filled with clues, tables, observations, and thoughts that become part of the investigation itself. Pay attention—something recorded there may be exactly what you need to move forward.

How It Works

Explore the rooms and pay attention to the details around you.

Search for clues that may reveal more than they first appear to.

Solve puzzles to unlock new situations and continue through the adventure.

Investigate the notebook and decide which clues, tables, observations, and seemingly stray thoughts might matter.

Why We Love It

It turns the escape room into a full book-length adventure. Across 287 pages, you’ll explore, investigate, solve puzzles, and work your way deeper into the mystery—no reservation or actual locked door required.

Observation matters. The pleasure comes from noticing details, making connections, and gradually understanding what the puzzles are asking of you.

The notebook is part of the mystery. Pages of notes, clues, tables, and observations turn the book itself into an artifact to investigate. You aren’t simply reading instructions—you’re examining someone else’s work and deciding what matters.

Cosmic horror makes a natural puzzle box. Strange discoveries, hidden information, and the feeling that perhaps you shouldn’t have opened that next door are right at home here.

Book Details

Type: Escape room adventure book
Theme: Cosmic horror / Cthulhu
Author: Gauthier Wendling
Format: Bound paperback
Pages: 287
Size: 7.5" × 5" × 0.75"
Features: In-world notebook pages, clues, tables & puzzles

There is one way out. Finding it is your problem.