What proprietary engine did Halo Studios move away from before Campaign Evolved?

Before Campaign Evolved, Halo Studios moved away from its proprietary Slipspace Engine.

Slipspace was created for Halo Infinite, which launched in 2021 after a long and difficult development period. Although it was presented as a major technological foundation for modern Halo, the engine's specialized tools and workflows were widely associated with development complexity and production bottlenecks.

In 2024, 343 Industries rebranded as Halo Studios and announced a shift toward Unreal Engine 5 for new Halo projects. Campaign Evolved was developed as the first major example of that transition, using Unreal Engine 5 for its rebuilt visuals and modern rendering capabilities. This change was intended to make development more efficient and help the studio create games for multiple platforms.

The common mix-up is choosing one of the rival engines listed in the answers. id Tech, Frostbite, and Creation Engine are associated with other game series; Slipspace was the proprietary Halo engine being replaced. Unreal Engine 5 is the newer technology adopted for Campaign Evolved.