Thinking with Time Machine
Developer(s)	Ruslan "Stridemann" Rybka
Publisher(s)	SignHead Studio
Engine	Source
Platform(s)	Windows OS X Linux
Release	April 18, 2014
Genre(s)	Puzzle-platform
Mode(s)	Single-player

Thinking with Time Machine is a 2014 modification for Portal 2 developed by Ruslan "Stridemann" Rybka, and released by SignHead Studio. The game revolves around the concept of a tablet-like time machine that is controlled by the player. The tablet allows the player to record their movement and replay the recordings, creating a double that performs the recored tasks. Additionally, the mod allows the player to see their own legs by looking down.

Initially released on the Mod DB website, Thinking with Time Machine went through the Steam Greenlight process, after which it was released as a free modification on Steam on April 18, 2014. The time machine concept and the ability for the player to see their own legs by looking down were commended by critics, while the lack of usage of the portal gun and the mod's short length were criticized.

Like the Portal series, Thinking with Time Machine is a puzzle-platform modification for Portal 2 played from the first-person perspective, in which the player must solve puzzles in "test chambers".^[1][2][3] Throughout the game, the player controls Chell, the protagonist of the Portal series.^[4] The player uses the portal gun that can create two ends of a portal, colored orange and blue.^[1][5]

In addition to the portal gun, the player is also given a tablet-like "time machine" in their left hand.^[3][4] Looking down at the tablet allows the player to record and control their movement, including walking, jumping, and picking up objects.^[1][3] After recording themselves, the player user can playback the recording, which summons a double who would perform the selected motion.^[3][4] Only one recording can be played at a time, although it can be replayed infinitely.^[3] This allows the player to perform multiple tasks simultaneously.^[6] Recordings can perform all the actions a normal player can, and the player can also stand on their double, allowing them to reach higher surfaces.^[3] After performing a new action, the previous recording is deleted.^[3] Another feature of Thinking with Time Machine is the ability for the player to see their own legs by looking down, which is not available in the Portal series.^[3][6]

The campaign starts at the end of Portal 2, after which the player is introduced to the time machine concept through a series of tutorials.^[3] There is no custom voice acting in the mod.^[7] Thinking with Time Machine features a level editor.^[8]

Thinking with Time Machine was developed by Ruslan "Stridemann" Rybka and published by SignHead Studio.^[9][10] Stridemann said that the development of the mod began after the release of Portal 2.^[7] Initially, the mod was published on the Mod DB website in 2013.^[7] "It took two years... there were ups and downs... I felt depressed and inspired... I wanted to give up so many times... but the desire to complete this miracle won out", Stridemann said.^[7] The mod later went through the Steam Greenlight process and was accepted due to the mod's concept.^[7][11] The mod was released on Steam for free on April 18, 2014, for Microsoft Windows, OS X, and Linux platforms.^[8][12][13] Considering that it is a modification, users must own Portal 2 to play Thinking with Time Machine.^[3][14] The game was one of the top 200 on Steam in 2014.^[9]

Christopher Livingston of PC Gamer praised the mod, saying that "it's very cool watching the past version of Chell appear and run through her recording".^[3] He commended the functions of the tablet, comparing the time machine concept to the cooperative mode, the ability of the player to see their own legs, and the tutorial puzzles.^[3] However, Livingston noted that certain puzzles, in which the double cannot be directly seen, "can get a little weird", while he also complained about the lack of usage of the portal gun.^[3] Phil Savage of PC Gamer praised the time machine concept and stated that the mod "dramatically expand[s] the complexity" of the Portal series.^[12]

Alice O'Connor of Rock Paper Shotgun also rated the mod positively, especially complimenting the ability to view legs in-game.^[6] Rock Paper Shotgun also listed Thinking with Time Machine as one of the best mods for Portal 2.^[15] Bo Moore of Wired praised the design of puzzles but noted that some puzzles lacked "Valve polish".^[1] He, however, criticized the mod for its short length and for not featuring many puzzles where the portal gun is used.^[1] Nobuki Yasuda of Automaton noted that the mod lacks a clear plot.^[7] Moore and Livingston compared the time machine mechanic to the 2010 The Misadventures of P.B. Winterbottom game.^[1][3] Becky Chambers compared it to the Braid video game.^[16]

• Thinking with Time Machine on Steam

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