In mid-October 1905, he somehow entered the lighthouse even though Murtaugh stated that he remembered locking it up earlier. Mur theorized that this was due to the cat's abilities to move across layers, and associated this with Albert Einstein's theory of relativity, and dubbed the cat "Einstein".
In a note dated 13th of December 1906 (one day after finding the Sanctuary), Murtaugh mentions that Einstein had disappeared yet again, implying that he has a history of coming and going like this. Murtaugh was stated to have grown attached to Einstein.
On one occasion, Murtaugh asked Elizabeth to take care of Einstein while he went exploring. Elizabeth accepted and returned Einstein to his own layer. Whenever Murtaugh and Elizabeth are not taking care of him, Einstein is taken care of by sunshine_bunnygirl_17.
In the last location of Submachine 10: The Exit, Einstein can be seen sitting over a shrine in the desert. Its posture is identical to the cat shown in the third secret of the HD version of Submachine 4, with an added tail.
Murtaugh has stated that Einstein has the ability to break the time and space barrier as he wishes. He also says that most cats might be able to do this. However, he also wonders if the appearance of the cat has anything to do with his ability and tendencies to draw karma portals. 
- The pictures from Submachine 4 and the SubVerse were of Mateusz's cats named Hator and Mimbla, respectively.
- ↑ Of Mur and Einstein note, Submachine 9: The Temple
- ↑ 2.0 2.1 Cat note from Submachine 2
- ↑ Note to myself from Submachine 2
- ↑ Letter to Liz from Submachine 2
- ↑ Letter from Liz from Submachine 7
- ↑ sunshine_bunnygirl_17 secret from Submachine 10
- ↑ Facebook, February 2nd 0:00
|Creator of the first Submachine - Einstein - Elizabeth - Henry o'Toole - King - King's Master Urbanist - Murtaugh - Predecessor - Predecessors - sunshine_bunnygirl_17 - Exploration team - Player|