Portal Stories: Mel is a single-player mod of Portal 2 developed by Prism Studios, a group made up of eight fans of the Portal series. The mod was released on June 25, 2015, for Microsoft Windows, OS X and Linux systems, available freely to people that own Portal 2 on Steam.
Like Portal 2, Portal Stories: Mel is a puzzle-platform game played from the first-person perspective as the player-character Mel. Shortly into the game's story, the player acquires a prototype version of a portal gun, which allows the player to create a connected opening on two different flat surfaces. This allows for accessing out-of-reach areas, passing objects, light, laser beams, and other matter through the portals, and using the portals as a means of "flinging" Mel or other objects across a level. These lead the player to various puzzle chambers that are required to be solved in order to access the exit point and proceed forward. The player-character can die by being shot repeatedly by automated turrets, falling into contaminated water, and other similar environmental hazards, but this will simply return the player-character to a previous checkpoint. Portal Stories: Mel adds a few new features such as water putting out fire, electrified water and a deadly version of the emancipation grill as well as using familiar puzzle elements from previous games in new ways, such as tractor beams, light bridges, and paint gels. There are a total of 22 levels in the game which the developers expect would take players from 6 to 10 hours to complete.
The mod starts when Mel, an Olympian from the 1936 Summer Olympics (said to have taken place in Nuremberg rather than Berlin), arrives by tram at the Aperture: Science Innovators headquarters in Michigan. She then enters the massive underground complex as a volunteer test subject on October 14, 1952. Aperture's CEO, Cave Johnson, speaks to Mel through prerecorded messages via intercom, informing her that she will take part in one of their smaller tests, the Aperture Science Short Term Relaxation Vault.
After the test goes wrong and she is put in suspension for decades, Mel is woken up and finds much of the facility in disrepair. She encounters a Cave Johnson impersonator telling her nothing is wrong and that she is still in 1952. Later on, it is revealed that the voice talking to her is a maintenance core named Virgil, who offers to help her escape from the facility if she helps him get back on a management rail he fell off. After helping her to obtain the portal gun, Virgil guides Mel through the remnants of the old facility, explaining that the destruction of GLaDOS (from the events of Portal) has caused most of the control systems in the facility to falter.
They continue upwards but learn that due to the reserve power coming on a prototype security system, AEGIS, has become active in the absence of GLaDOS and is tracking them through the facility, trying to eliminate them after mistaking them first as unregistered life forms then as potential threats to the long dead scientists. Virgil realizes the only way for Mel to escape is to disable AEGIS.
After traveling through some old and overgrown test chambers, the duo eventually arrive at AEGIS's central core. After a battle with the AI, Mel enters the code to shut down AEGIS, not before finding out that AEGIS was attempting to destroy GLaDOS as well. Virgil leads Mel to the elevator, has her destroy the portal gun, and says his goodbyes as she ascends to the surface. Mel opens a door leading to the outside world to find the same town she walked through decades ago to get to Aperture both modernized and in ruins.
In a post-credits scene, AEGIS has enough power left to initiate one final fail-safe: waking up the test subject Chell, the main protagonist of the Portal games, by draining the reserve power so she can escape, setting up the events of Portal 2.
Portal Stories: Mel was developed over the course of four years by a small independent team of fans under the name Prism Studios. Development for the mod started in May 2011, and the mod was originally intended to launch early 2012. After several delays, on March 21, 2013, it was announced that the focus would be changed primarily to quality. At this point, the development team had completely changed.
On August 4, 2013 the first closed beta for Portal Stories: Mel was announced. As a result of this beta, several maps were re-worked and updated to higher quality standards. The team was also saw the addition of a new Modeller and an extra level designer. On June 20, 2014 the development team announced that they were aiming for a release in the first quarter of 2015, with support for Windows, OS X and Linux systems.
On July 26, 2014 the mod was put on the Steam Greenlight program, together with a teaser trailer posted on YouTube. On August 1, 2014 the mod advanced through Steam Greenlight. After being successfully green-lit, the developers started posting Development updates at the end of each month, discussing what had been done and what the plan was for the next month. Alongside this, the developers also started a new closed beta, which expanded every month with new players to gather more feedback. In their February Development Update the developers announced that they had to once again postpone the release.
On June 25, 2015 the mod was released on Steam. Several developer commentary videos were released on YouTube shortly after.
In response to complaints about the difficulty of the mod, the developers announced that they were working on an optional "Story Mode" difficulty, with reduced puzzle difficulty. This mode was released on August 31, 2015
The game was generally well received by fans of the series. Both PC Gamer and the Washington Post, among many other media outlets wrote positive reviews for the mod. As of November 15, 2015, the mod has a rating of 93/100 on Steam.
Portal Stories: Mel won the award for "Best Fan Creation" at The Game Awards 2015.