The exit door may be closed and require a button to be held down to open, or atop a higher platform out of reach, or may not be immediately visible.
This process can be repeated indefinitely, allowing the player to manipulate these scalable objects as to create platforms to reach the exit or clear obstacles blocking them.
They are put to sleep and placed in a testing environment constructed in their dreamworld, where they are capable of performing reality bending feats such as changing the size of items based on perspective or instantly creating copies of them.
Meanwhile, the AI administering the dream therapy advises the player to initiate an "Explosive Mental Overload" in order to trigger the "Emergency Exit Protocol" and escape the dreamworld.
Eventually, the player travels through enough dream layers to trigger the Emergency Exit Protocol, but it fails due to an unknown error.
Superliminal was developed by the six-member team of Pillow Castle, led by Albert Shih, a student from the Entertainment Technology Center (ETC) at Carnegie Mellon University.
"[1] He improved upon the concept during his graduate work, establishing Pillow Castle in January 2014 and obtaining assistance from four other ETC students to build out the game.
[2] Shih had been inspired by successful games like Risk of Rain and Antichamber that had been made by small teams to continue his work on Superliminal.
[1] Antichamber was particularly influential to Shih, as it directed and encouraged the player to think outside the box to discover the solutions to its puzzles, an idea he wanted to recapture in Superliminal.
[3] The scaling puzzles proved to have some trouble in playtesting since players could come up with possible solutions that ultimately were not working and the game unable to provide feedback for why.
[4] The tech demo was publicly released in January 2014, along with submission into the Independent Games Festival (IGF) Student Competition for 2014,[5][1] where it won along with Risk of Rain and Engare.
A free update in November 2021 brought a time-limited experimental multiplayer mode called "Group Therapy" to the Windows version based on the battle royale genre, where up to twelve players race through randomly-generated puzzle rooms to reach the exit to each first.
[15] A cooperative mode that allows up to four people to play through the game's story and five additional "Group Therapy" maps were added in a free update in December 2021.