Psychological Instability is an incredibly short series of puzzles made for the original Portal by Valve, utilising advanced gameplay mechanics beyond that which lies in the main campaign. All of the music in the map is completely original.
Production of the map began on June the 1st, 2014, and stopped around a year after, leaving only three chambers and an unresolved story, the last chamber unreleased until March the 30th, 2017. The intention was to make two more maps to follow the first up, but time was of the essence. Experiencing Death First-Hand and My Companion (the last two songs included in the soundtrack) are not present in the mapset.