Halo Wars 3
From Halopedia, the Halo wiki
A rejected pitch for Halo Wars 3 was unveiled in 2017, through the release of concept art. The pitch was primarily concerned with concepting how space combat could work in a Halo Wars game, indicating that the proposed game would likely have featured space battles, but it also references ground combat, which the series is known for. Ultimately, the pitch was rejected, and the proposed game was never made, with 343 Industries confirming in February 2021 that it still had no plans to produce a sequel to Halo Wars 2.
Most concept art for the pitch revolved around space combat, a style of gameplay that would have been new to the Halo Wars series. In this mode, a capital ship would have served as the player's home base, from which the player would prepare and deploy their ground forces. This ship would have been customisable and upgradeable, with various rooms providing different stat boosts and some even buffing the ship itself in ship-to-ship combat. These buffs would affect aspects of the ship such as shields and thrusters.
Despite the focus on the capital ship itself, other ship types would also have been available as units for the player to control, similar to how ground units are controlled in the previous two games. One piece of concept art depicts a Stalwart-class light frigate with an escort of Longswords and other fighters, all highlighted as individual units. Meanwhile, various other pieces of artwork show large-scale battles involving many ships of various types, including both UNSC and Covenant vessels.
Although the pitch mainly concerns space battles, ground battles would still have been present in the proposed game. Brad Wright mentioned the capital ship as where the player would prep their ground forces. Additionally, a concept piece exists showing six different potential land environments, complete with UNSC units traversing the terrain.
The Halo Wars 3 pitch was produced at some point before October 2017, by Creative Assembly. Artists Brad Wright and Bill Yi created concept art for the pitch, illustrating the proposed space battle mechanics, as well as concepting environments for the game, both on land and in space. The pitch was shown to Microsoft, but was ultimately rejected.
In October 2017, Brad Wright received permission from Microsoft to share the artwork he had produced for the pitch, and posted it on ArtStation, alongside other concept art for a pitched version of Halo Wars 2: Awakening the Nightmare which would have included Promethean enemies. However, shortly thereafter, the comments mentioning Halo Wars 3 were removed, and replaced with a generic description, describing it as additional work done for Halo Wars 2. Ultimately, the artwork was removed entirely.
Much later, in 2020, Bill Yi also uploaded concept art for the pitch to ArtStation and his personal website, identified by filenames including the abbreviation
In February 2021, 343 Industries announced that it no longer had plans to support Halo Wars 2 with subsequent content updates or balance patches. As part of this announcement, the company also reaffirmed that at the time, no new games in the Halo Wars series were in production, though didn't rule it out as a possibility in future.
The artwork produced heavily featured the UNSC Frontend, a stand-in ship for the ship that would be featured in gameplay, named after a term in game development and software engineering which means the user-facing portion of a system. The placeholder ship is described as an "M-class carrier" and has a registry of "18384973-YU". The ship was constructed in the "Outer Sol Docks" and was captained by "Captain Steve". Another concept piece labels the year as 2567, adding that the ship is in "Low Ark Orbit" and at Alpha Centauri. All of these details are almost certainly placeholders, serving as a proof of concept rather than being representative of the story and lore of the pitched game.
Visually, the ship is a kitbash of various existing Halo ship designs, likely done to save time during the concept art process. It uses the Halcyon-class light cruiser as a base, with elements grafted onto it from various other designs, including the Paris-class heavy frigate, the Phoenix-class colony ship and the fan-made "Nevada-class heavy frigate".
Brad Wright's concept art
Bill Yi's concept art