The Girl Genius Sourcebook and Role Playing Game is a project of Studio Foglio working with Steve Jackson Games. Utilizing the GURPS system, the sourcebook allows users to play their own adventures in the Girl Genius Universe. After being in on and off production since at least 2004, the project was finally let loose on the world in August 2021 as a prerelease PDF, with a forthcoming Kickstarter for the final printed version.
In a first for the Girl Genius franchise, young Victor Foglio is officially listed as being one of the product's creators.
Prior to release, Lady Foglio indicated that the book contains a large amount of background information, including some from the Secret Blueprints Vol. 1, and that it is effectively Vol. 2 of the Blueprints and therefore somewhat spoilery; this has been confirmed by purchasers of the PDF, it does indeed contain information not yet revealed in the comic or the Girl Genius print novels, such as an outline of the situation with/in The Americas.
The book contains an eight-page story, Mayhem ex Machina!.