An elevator is a new type of sector action and thinker, originally introduced by the Boom source port, which moves the floor and ceiling of its sector together, forming a construct similar to a real-life elevator.
Boom elevators can be made subject to three distinct line actions. All Boom-compatible ports have support for these actions. All of the types are applied to a sector by tagging the line with the action the same as the sector. Unlike most other actions in the Boom engine, elevators were only implemented with walk-over and switch triggers; there are no manual push or gunshot activated elevator actions. Some source ports may add the ability to create such triggers, for example through support for the Hexen map format.
- "Elevator up" (line actions 227, 228, 229, and 230) moves the elevator so that its floor is level with the next highest adjacent floor. This action can be repeated, and the elevator will move up to the next higher floor each time so long as another higher adjacent floor exists. If none exists, no motion takes place.
- "Elevator down" (line actions 231, 232, 233, and 234) moves the elevator so that its floor is level with the next lowest adjacent floor. Likewise, this is repeatable and the elevator will move down to the next lower floor each time until it is level with the lowest surrounding floor.
- "Elevator here" (line actions 235, 236, 237, and 238) moves the elevator so that its floor is level with the floor on which the activator of the line action is standing.
All Boom elevators move their floor and ceiling together at a speed of four map units per tic. If either surface encounters an object blocking its motion, the elevator will wait until the obstruction is removed before continuing toward its destination. Elevators never inflict crushing damage. They make the same sounds as regular moving floors. Advanced source ports may make some or all of these aspects customizable.