ShiftFS
ShiftFS is the in-game filesystem format for ShiftOS.
In the introduction sequence for 0.0.x releases of ShiftOS, the operating system would format the player's C: drive and repartition it with the "ShiftFS" filesystem format. In reality, this was the game creating the C:\ShiftOS folder - the player's save file - and creating all the folders and files necessary for the in-game environment. The rest of the introduction screen would be reserved for creating the illusion of installing an operating system on the player's drive, well after this save directory was generated.
This filesystem format allowed the game to sandbox its filesystem outside of the host computer's. This meant that the player truly could not go above ShiftOS's root folder, a feature in 0.0.x.