So if anyone is able to get a hold of the old Gearbox port of Halo to the PC, much like some other classic games (Dawn of War, Empire at War) you will find there is a modding community dedicated to enhancing and extending the experience of the old product. Well now there is a single player campaign mod called SPV3 and what it does is update the campaign so to speak of the classic halo. New enemies, and new weapons some directly from the sequels that wasn't in the first game, others translated a bit. Some levels have been redesigned, some new levels have been added altogether. Including one level The Commander in which you play as the Arbiter as he was before he became a disgraced Zealot when the Halo rings blew up.

They have also added another separate campaign called Lumoria which was another mod but is being adapted to be compatible with SPV3.

Now it is a mod so there are some hitches to it as with many mods. Stability and the post processing visuals have made things hard to see which works well in some but sort of doesn't work well (i.e. flood levels are much scarier but not being able to see grunts in front of you is frustrating).

But if you still have Halo on your PC and decide to give it a try to see what it could do then go for it. Although I would recommend starting on Normal first unless you like being a glutton of punishment and go for Legendary or Noble (they removed Easy mode).