Halo 2 Vista product key for $1 from humble weekly bundle right now. : r/HaloOnline
Halo 4 CD Key for Xbox One / Series X (Digital Download)
Halo Custom Edition CD Keys - YouTube
How to run Halo Custom Edition on Linux with community mods
Halo Infinite: Campaign Global Xbox One/Series/Windows CD Key – RoyalCDKeys
But can you do it on Windows 98? on X: "You can play Halo: Combat Evolved on Windows 98 WITHOUT KernelEX. Another interesting case of Windows 98 being an officially supported platform!
How To Install A Custom UI Mod In Halo CE | Yuri Shwedoff