This free "Halo: Combat Evolved" PC mod introduces VR support to the original shooter game. - Road to VR
This Free ‘Halo: Combat Evolved’ PC Mod Brings VR Support to the OG of Shooters
A mod named 'HaloCEVR' lets you experience the original PC version of Halo: Combat Evolved in VR, with added motion controller support. Created by modder 'LivingFray', this mod enhances the game with features like first-person shooting, two-handed aiming, and motion-controlled actions. However, it only works with the 2003 PC edition, not the remastered version in The Master Chief Collection. To get started, you'll need the original game, a separate patch, and the mod itself. Check out the detailed installation steps and explore the full story at Road to VR.
Source: https://www.roadtovr.com/halo-combat-evolved-vr-mod-steam-vr/