Acid

Released in 1999 as a Japan-exclusive, Acid (published by Taki) is one of the more obscure and avant-garde action titles in the PlayStation's library. Often confused with the later Metal Gear Acid series due to the name, this title is entirely unrelated. It is an abstract, first-person action game that places a heavy emphasis on psychedelic visuals and a "labyrinthine" atmosphere. Players navigate through surreal, brightly colored environments that shift and pulse, creating a sensory experience that was highly experimental for the 32-bit era.