Portal Stories: Mel is a single-player modification based on Portal 2 using the Source game engine. The mod was developed by Prism Studios, a group made up of eight fans of the Portal games. The freely-available mod was released on June 25, 2015, for Microsoft Windows, OS X and Linux systems. Like Portal 2, Portal Stories: Mel is a puzzle-platform game played from the first-person perspective as the player-character Mel, a test subject for Aperture Science. 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...