Portal Revolution

Portal: Revolution is a 2024 free modification for Portal 2 created by Second Face Software. As with the official Portal games, it is a puzzle-platform game that involves using portals to navigate test chambers. It also adds several new mechanics, such as suction vents and paired laser cubes. Taking place prior to the events of Portal 2, players control an unnamed test subject as she attempts to gain control of a device that will restore the Aperture Science testing laboratories to full condition.

After its initial release was delayed due to approval difficulties, it was distributed on Steam and was largely praised by critics.

Gameplay
Like in the official games in the Portal series, Portal: Revolution's gameplay is based around solving puzzles in "test chambers". Players use a gun to manipulate the environment using portals, interacting with mechanics such as buttons and cubes. They can also coat the chamber in gels, which can adhere to surfaces to make the player bounce or slide across them.

Additionally, the mod incorporates several new gameplay elements such as a shower that cleanses gel and paired cubes that facilitate the transportation of laser beams. It also reintroduces "Pneumatic Diversity Vents" which can suck up other test elements; these were removed from the original version of Portal 2 during its development. Some test chambers also add switches that can turn off the power, which disables barriers but also turns off devices that help the player. A significant number of puzzles in the first half of the game only allow the player to control one portal, with the other being placed in a fixed position.

Plot
Portal: Revolution serves as a prequel for Portal 2, being set after the events of Portal. In game, the player assumes the role of an unnamed test subject in the dilapidated laboratories of Aperture Science. The game begins with the protagonist being awoken by a maintenance personality core, Stirling, who tells her that she is being trained as part of an "emergency response team", and instructed to solve a series of tests.

After completing them, Stirling reveals that he was misleading her, and his real goal is to activate a powerful device which will restore Aperture's laboratories to full operation. He asks for the protagonist's cooperation in exchange for setting her free. Traversing both maintenance areas and test chambers, they reach the "Spire" where this device is located. Stirling explains that this device expands on Aperture's previous work with teleportation, allowing him to use it to reassemble and activate GLaDOS. The protagonist enters the device control room and Stirling instructs her to test it by teleporting a short distance, but it malfunctions.

The malfunction causes the protagonist to be teleported to an older experimental testing track. There, she meets up with Emilia Conly, a former Aperture employee whose mind has been copied into a core. Conly and the player traverse the experimental test chambers, eventually reaching the base of the Spire. Ascending the Spire, Conly warns the test subject that Stirling's reactivation of GLaDOS will lead to disaster, as she previously killed all the test subjects and Aperture employees when she was awake, including Conly's original counterpart. Conly and the protagonist navigate through more test chambers, eventually reaching the top of the Spire, where they meet with Stirling. Conly tries to reason with Stirling, but he refuses to change his plans, stating that the facility needs GLaDOS.

After going through test chambers close to the surface, Conly and the protagonist reach the device control room once again. There, they fight with Stirling to disable the device and stop him from awakening GLaDOS. During the fight, Conly reveals that Stirling was originally a robotic vacuum cleaner that she created. Conly and the protagonist successfully stop Stirling from using the device, which explodes. In a post-credits scene, it is revealed that the explosion of the device led the Spire to be teleported to the moon, stranding the protagonist and Conly there. The former passed out and was seriously injured, leading Conly to place her in a lunar long-term relaxation vault.

Development and release
The Austrian lead developer, Stefan Heinz, began working on Revolution as an after-school hobby project in 2016, after being inspired by mods such as Portal Stories: Mel. The team eventually expanded to eight people located in various countries, including 3D modellers and graphics programmers. Many of its members learned the skills they needed during the game's development. Due to increasing internal expectations, much of its content was replaced or revamped as development progressed, and the team revamped some of Portal 2's assets to increase their quality. The game uses Strata Source, a community-made version of the Source engine with modern features that the developers state are "impossible in Portal 2".

The game was initially envisioned as having a 2022 release date, but took longer to develop than expected, leading to it being delayed into 2023. It was finally slated for a release date of January 5, 2024, but Valve failed to approve it by the intended date. Heinz stated at the time that "the game is done" but Valve's review was prolonged due to reduced staffing during the holiday period. He initially got the impression from them that the release date would be viable, but after submitting the game for release had failed to get a response as the deadline approached.

Instead, it was published on Steam on January 6 for Windows and Linux. Before release, Heinz indicated that the team intends to add post-release content, such as a developer commentary and a separate version of the soundtrack; the latter was released on April 1 alongside a decorative DLC designed to support the developers.

Reception
Portal: Revolution received an "Overwhelmingly Positive" rating from over 900 players on Steam a day after its release. PC Gamer writer Morgan Park stated that it had a "high bar of quality and completeness" that proved "Valve left a lot of meat on the bone with the Portal series". Ford James of PCGamesN described it as being "refined to the point where it could feasibly be DLC from Valve itself".

Both Park and Elie Gould of TechRadar complimented the puzzle design, with the latter praising the puzzles as being "no different" from the challenge of the original game. James called the puzzles "consistently strong", stating that the restriction on shooting portals in the first part of the game "is often used to great effect". Writing for PC Games, editor Felix Schütz praised the new mechanics, saying that they helped keep the game fresh.

Gould said the game had a "story to die for" that "fits nicely" with official Portal games. Schütz described its writing as "absolutely successful" and impressive, though not on the level of Portal 2. Park criticised the writing of Stirling in the initial chapters, stating he failed to put "'personality' in personality core", but noting he didn't detract from the overall quality of the mod. James agreed, saying he was "perhaps the weakest aspect of Revolution", but praised the character of Conly in the second half.

However, Park complimented the visual design, stating that he "didn't know Portal 2 could look this pretty". Praising the atmospheric variety of the game, Schütz stated that the quality of the environments helped it fit into the Portal universe.