Portal Stories: Mel is a singleplayer mod for Portal 2 developed by Prism Studios.
The game is set in 1952. Mel, an Olympic champion, arrives in an unnamed small town in Michigan where the headquarters of Aperture Science is located. Mel was invited to participate in a test of Aperture Science Short Term Relaxation Vault. Mel arrives at the vault, gets into it and falls asleep. But something goes wrong and instead of several minutes, Mel sleeps for several decades. Upon coming to, she finds that the Aperture Science facility is devastated. Mel has to get out of there.
The gameplay of the mod is not different from Portal 2's. The players solve puzzles using the portal gun which allows for opening two two-sided portals on suitable surfaces and moving different objects. Almost every object from Portal 2 is present in the mod with one new addition: water. It is used to extinguish a fire. The game consists of 22 puzzles and takes from 6 to 10 hours to complete.