Cut Halo: Reach vehicles
From Halopedia, the Halo wiki
Armoured personnel carrier
Labelled in file uploads as the "Wolverine" and "Kodiak" at different stages, various concept images released by Isaac Hannaford indicate that at some point in the development of Reach an APC was planned for inclusion in the game. Few details are known of this vehicle, and it is likely it was never realised in 3D or in-engine prototyping. The vehicle notable bears an extremely heavy resemblance to the M577 APC from the film Aliens - one of many inspirations taken from the Alien franchise as a whole.
The release of Halo Wars in 2009 saw the introduction of the M9 Wolverine - an anti-air tank employed by the UNSC. It is likely that this spurred the change of the APC's name from Wolverine to Kodiak. The release of Halo Wars 2 in 2017 saw the introduction of the M400 Kodiak - a self-propelled artillery vehicle bearing little resemblance to the planned Reach vehicle.
Code referencing the Wolverine as a vehicle physics model remains in the files of Reach[Note 1]; the vehicle operates in a similar manner to other human vehicles such as the Warthog and Mongoose, though has an additional deployed state.
Once notable vehicle heavily prototyped in-engine was a UNSC watercraft, a small attack boat capable of seating a driver, a passenger and a gunner on an M41 Vulcan - akin to the Warthog. Early campaign level layouts by Marcus Lehto indicated an intent for the fourth level of the game to be a "covert SEAL-esque boat attack at night", with the goal of sinking a ship.
The boat was concepted by Isaac Hannaford, and prototyped extensively in-engine resulting in the development of water-wake technology later re-used for the jet-wash effects on the jetpack. Ultimately, the boat was cut entirely, though the boat's removal was credited in allowing the level New Alexandria to be fully-developed and make it into the final game. A small amount of footage of the boat prototype was later shown at PAX 2010 in a demo reel of cut content; showcasing the boat riding on the waves and driven in a third-person view.
Code for the boat remains in the files of Reach.
Referenced only in the game code, the "Jackal glider" was presumably an aerial vehicle designed for the Kig-Yar. The glider's physics model is extremely advanced compared to all other aircraft in-game, containing data fields for wings, tail, rudders and drag among other things.
While the Type-47B Scarab did ultimately make its way into the final game as a low-poly background entity on the levels Tip of the Spear and The Pillar of Autumn (with the latter level also featuring a more detailed, non-interactive setpiece Scarab at one point in the mission), early ideas for the game's campaign were to have the player character able to drive the Scarab. Early ideas for the level New Alexandria would have seen the player drive the Scarab in the remains of the post-glassing city. Prototypes for the Scarab were made and the physics involved described by Chris Ophdal as "sweet", though the Scarab was ultimately considered unsustainable - especially with the high engine cost needed to run the level. Ultimately, the drivable Scarab was scrapped and New Alexandria was transformed into an aerial mission focusing on the Falcon instead.
Cut dialogue for the missions Tip of the Spear and Exodus shows that early plans for these levels were for both to feature Scarab encounters similar to those featured in Halo 3 and Halo 3: ODST, though all were cut.
Referred to internally as the "siege engine", little is known of this gargantuan Covenant vehicle's purpose. The vehicle was concepted by Isaac Hannaford, though never progressed past the concept stage. When asked about the vehicle's resemblance to the H-K-Tank] from the Terminator franchise, Hannaford responded that there were "no coincidences.
Some concept art for the Tip of the Spear mission indicates that early plans were to have the siege engines be the target of the Battle at Szurdok Ridge. This early concept may also be depicting what would have been mission nine in Lehto's early campaign level layouts; which list a mission with the following objectives;
The "massive hover platforms" mentioned match the visual depictions of the siege engine.
Halo 3 leftovers
Code remains in the files for the physics models of several leftover vehicles used and/or cut from the previous game, Halo 3. These include the Chopper, Mantis and Guardian Sentinel (classed internally by the game as a vehicle).