Portal Stories: Mel

Portal Stories: Mel is a modification and unofficial prequel to Portal 2.

Mechanics
Portal Stories: Mel's mechanics work similarly to Portal and Portal 2.
 * New '70s portal gun model
 * '50s mobster Turrets (Voices unused due to the Source Engine's programming)
 * Advanced, high-difficulty tests
 * Stylish '50s Long Fall Boots
 * Death Fizzlers

Mel
Mel is the main protagonist of Portal Stories: Mel. She is a middle-aged brunette woman sporting a brown Aperture jumpsuit and spring based long fall boots. She also has minimal makeup such as red nail varnish and red lipstick. Little is known about her history as she is a silent protagonist similar to Chell from Portal and Portal 2,

Virgil


Virgil is a personality construct, built by Aperture Science, probably in the late Cave Johnson/early Caroline era of the company as one of the first cores, due to his eye being the '70s logo of Aperture, as well as him having a great deal of knowledge on the older facility. He has a dark red skin with a tropical theme, and his orange eye cracked. Being a personality construct, he is a sentient AI and has a personality as the title implies. Throughout the game, he is shown to have much more intelligence then Wheatley, but he is simply referred to as a maintenance core and does not possess a defined personality trait like the Space Sphere, Rick or the Fact Sphere.

Seeing that Portal Stories: Mel is non-canon it is unknown what truly happens to Virgil after the game or in the time period of Portal 2. Finally, it is also inferred that Virgil maybe be homosexual or bisexual as he shows some subtle attraction to the Rainbow Core, who is a male personality core.

AEGIS
AEGIS (Aperture Employee Guardian and Intrusion System) is the main antagonist of the game. He can speak and make autonomous decisions, but they are based on protecting the scientists and does not show any self-awareness or sentience. He can only follow protocols and what will be safest for the scientists. He also seems to have great power over the facility, like GLaDOS, such as dispensing turrets, starting a flooding sequence or a asphyxiation program and even control testing tracks. He is first encountered in old Aperture when you have almost escaped the Lima Whiskey testing track as its radars can probably pick Mel up and immediately deems you as a threat, assuming you killed all the scientists in the Bring Your Daughter To Work Day incident.

Rainbow Core
The Rainbow Core appears as an Easter egg in a Test Chamber involving Excursion Funnels, and speaks in a similar fashion to the Adventure Sphere. Virgil seems to be attracted to him, as evidenced by Virgil hoping Mel 'got his serial number'.

Trivia

 * The original Portal 2 was going to be a prequel and the main protagonist was also called Mel, but the two are mostly different characters and this beta Mel would go up against a southern Cave Johnson in the early days of Aperture, however it was changed to a sequel with Chell and GLaDOS because people missed Chell and GLaDOS' relationship, so Mel was scrapped.
 * Ratman's dens can also be found in Portal Stories: Mel and one depicts AEGIS with millions of hands, depicting its control over the facility, when it is online.
 * A hidden companion cube can be found in Chapter 4, and is immediately fizzled on attempts to pick it up.
 * The number "2056" appears many times during the game, in a mysterious way. It can be found at the beginning of the game on the train, and many other times, appearing also in an Easter egg and an achievement. This is a reference to developer LoneWolf2056's username.
 * At the end of Chapter 4 a portrait captioned "Wallace Breen visits Aperture Science Laboratories, 1983" can be found depicting Wallace Breen shaking hands with Cave Johnson.
 * There is possiblity to open Puzzle Maker in this game. Open console and write  to open new map, and   to see dialogue window with saved maps. However, all of the models and textures are missing, and you can't actually play the chambers.