Duke Nukem 3D "Build" engine had doors/walls that can move sideways. The "Build" scripting system allows a whole string of moving and sliding parts with sound effects, such as buildings falling down, earthquakes, and walls that break apart when hit with explosives. One of the more advanced effects is the horizontal sliding platform that can move the player inside a small sliding room, which made it possible to create subway cars moving in a timed sequence around a ring-shaped track.