Unlike previous entries from Halo franchise, 2021 Halo Infiniteruns on a proprietary engine called Slipspace. This engine, created in-house by 343 Industries, was designed to accommodate the game's semi-open world design while retaining the classic Halo the game feel that players have come to know and love. Slipspace was largely able to achieve what it set out to do, but it caused a lot of problems along the way Halo Infinitehis development. Compared to other contemporary software, the engine was frustratingly difficult to work with, largely because some of the coding toolsets it used were really outdated. The heavy reliance on 343 contract workers didn't make things any easier as each new developer was assigned to work on Infinite he had to be trained to use Slipspace.
Difficulties caused by the Slipspace Engine and the constant cycle of contract workers at 343 Industries contributed to major failures in Halo Infinitehis content channel. At launch, the title lacked various multiplayer features that were a staple of the game Halo series, such as split-screen co-op. Some of them were eventually added in later content updates, but post-release support for Halo Infinite it was so slow that player count and overall sentiment towards the title dropped considerably over time. To fix this problem, Microsoft recently announced that all future Halo games will be developed on Unreal Engine 5 from now on. This change for Xbox's flagship franchise is significant and could be the catalyst for other primary MS studios to move to UE5 as well.

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Many Xbox games already run on Unreal Engine
Microsoft is no stranger to using the Unreal Engine for its primary games. Many of the company's recent titles already use Epic Games' popular software. Sea of Thieves, Senua's Saga: Hellblade 2, Gear wheels 5and even Grounded are all games that run on some form of EU. In addition to these titles and the following Halo game, a significant portion of upcoming Xbox mainstream releases also use Unreal Engine 5. inExile's steampunk RPG The mechanical revolutionof the Initiative Perfect darkness reboot, and Compulsion Games' Southern Gothic action-adventure title South of midnight these are just a few examples.
A significant amount of Microsoft's primary studios use proprietary engines
Despite the many UE5 games it develops, Xbox still uses and owns the rights to a small number of proprietary engines. idTech, for example, is the flagship engine designed by Microsoft's subsidiary id Software and is primarily used in games published by Bethesda Softworks, such as Doom Eternal and the future Indiana Jones and the Great Circle. Starfield, Fallout 76and other Bethesda Game Studios titles, meanwhile, run on the Creation Engine, while Zenimax Online The Elder Scrolls Online use HeroEngine. Then there's ForzaTech, which is the namesake engine used in both FORZA franchise and 2025 Fable reboot. Another Microsoft-owned engine worth noting is Call of dutyhis IW engine.
Dubbing on Unreal Engine 5 could benefit Xbox in various ways
A number of engines are used in the primary studios of Xbox, but as in the case Halo series, Microsoft may want to consolidate them and shift most of their resources to Unreal Engine to make development easier. After all, if every developer under MS used the exact same engine, it would be much easier for them to support each other more often. This, in turn, could allow Xbox games to be released at a faster pace.
A wider pivot to the Unreal Engine may also allow Microsoft to hire contract workers on a more frequent basis, as they are usually familiar with well-documented engines like UE. While it's unlikely that Xbox will cancel all of its proprietary engines, encouraging its primary studios to use UE5 could be a way for the company to prevent certain situations, such as Halo InfiniteSlipspace's tumultuous development, let it happen again.