Portal Reloaded

Portal Reloaded was released on Steam for free on April 29, 2021, as a full-scale mod featuring a custom soundtrack and story.

[2][3][4] Unique to the mod is a third "time portal", colored green, which allows the player to go between the same point in two alternate versions of the test chamber, one in the past and one in the future.

[6][7] The game also involves solving puzzles with other testing elements introduced in the official Portal series, such as buttons, cubes, lasers, and light bridges.

[2] If an object, such as a cube or a conventional portal, is manipulated in the past, it will also move in the future chamber, causing the prior duplicate to fizzle.

[11] The developer stated that the mod is intended as a smaller-scale complement to the original game, in contrast to other modifications such as Portal Stories: Mel.

[14] Navigating various test chambers using the portal gun, they learn how to use time portals to navigate between a version of Aperture's laboratories in the past and a dilapidated and broken version twenty years in the future, which the facility's artificial intelligence overseer states has been damaged as a visual aid.

As the game progresses, it is revealed that the main character was the only one who survived initial time travel, and that Aperture cannot get it to work in any way other than the twenty-year interval.

Near the end, the overseer admits the Enrichment Center was in fact destroyed under mysterious circumstances involving a "rogue test subject".

They reveal the actual purpose of the testing track – to train the player character to kill the rogue subject, preventing the destruction of Aperture's facility.

If the player does the former, the test subject successfully returns to stasis, with the AI commenting that they will now "change the course of history", possibly causing the events of Portal to never happen.

[10][21] Rick Lane of PC Gamer did not consider the time portal mechanism to be particularly stunning, but he did laud the game for how it used the idea.

[17] Lane remarked that Portal Reloaded "recaptures the wow factor of the original game", but felt that the additional elements in the puzzles could cause frustration occasionally.

A schematic containing two versions of a test chamber, each a platform separated by height. At the top, the chamber contains a portal opening located at the bottom of the gap, leading to another on a wall high above the lower platform. A human figure is shown to be able to navigate from the lower wall into the bottom portal and exit from the top portal. Alternatively, they can enter the square time portal to access the bottom chamber, which has the other portal openings positioned differently.
In this example, the player can either use the blue portal to exit from the orange portal, or enter the green "time portal" to access the future chamber, where the other portals are positioned differently.