Engine

The term engine could refer to the following:

Ground vehicles

 * Hydrogen-injected internal combustion engine - An engine used to power UNSC ground vehicles.
 * Boosted gravity propulsion drive - Engine used to power Ghosts, Banshees, and other Covenant vehicles.

Spacecraft

 * Fusion drive - The primary sublight propulsion system on human spacecraft.
 * Repulsor engine - The primary type of Covenant sublight engine.
 * Impulse drive - A type of Covenant sublight engine.
 * Reaction drive - A Forerunner sublight engine.
 * Slipspace drive - A general term for devices used to transition in and out of Slipstream space.
 * Shaw-Fujikawa Translight Engine - The human version of the slipspace drive.

Real world

 * Halo 3 Engine - A game engine used to power Halo 3 and Halo 3: ODST.
 * HAVOK Physics Engine - Used for Halo 2, Halo 3, Halo 3: ODST, and Halo Wars.