The World Machine, designated Project: Orbis Tertius, was a reconstructed Earth (Planet D-0-2-R-L) used as an experiment by the Pageant . It resulted in an alternate 1804 where the French Revolution did not end.
Interested in the relationship between individual psychology and the historical dynamic, the Pageant Maskmaker Goodfellow, an artist-scientist, was put in charge to conduct the study, not to hurt humanity but simply to see how they would react if history was different.
In 1794 they approached the Marquis de Sade for his philosophies and offered him the chance to change the world, to which he agreed. Earth was removed from space-time and placed in a pocket universe, the surface now covering the massive "World Machine" that could regulate and control the physical nature of the planet. Sade later became sensitive to the Machine and could see it through his shadow, speaking of "gaps in the air" and "worlds in the gaps."
Minski was created as the System Operator and programmed with an epistemic code based on Sade's philosophies and ideals, but this corrupted his system. He became independent and took control of the Machine. Goodfellow became trapped within the Machine, Sade was locked away in the reconstructed New Bastille and Minski began dominating France through a clockwork replica of Sade who claimed First Deputy Minski as his adopted son. Parisians, especially women, were both fearful of Minski and fiercely loyal to him, willing to lay down their lives for him. There was a curfew for Parisians and anachronistic technology, such as steam driven carts, were utilised. There was also Minski's murder machine, a labyrinth of execution tools into which a person would be thrown and would eventually die.
As a result, the French Revolution continued until 1804 with America and England being purported as Devil worshippers. The other leaders of the world, some actually members of the Hellfire Club, were organised by the Pageant to attack France. Meanwhile, Minski engineered a virus that would allow him direct control over individuals.
The First Doctor and Dodo Chaplet visited this reality and combatted Minski, the Doctor eventually confronting the Pageant. With Minski dead, they retook control and assured the Doctor they would return Earth to its original space-time while the Doctor assured them that any further experiments would be brought to a swift end. (PROSE: The Man in the Velvet Mask)