Well first you have to be able to enter cheats, and to do that you simply, right click on the halo desktop icon, then go to properties, then add -console -devmode. be sure to put a space between -console and -devmode. (WARNING: could mess up game in some way that I am unaware of). Then go to Halo, go into campaign. Then press ~ (tilde key). You will then see a pink word in one of the corners. That is when you type in the cheat codes.
Invincibility: cheat_deathless_player <0
Well, Halo Custom Edition is the multiplayer version of Halo Combat Evolved PC. It doesn't have a Campaign, by the way. If you want to get Halo Custom Edition, install the installer and use your Halo Combat Evolved PC Key. The main advantage of Halo Custom Edition is custom maps. Halo Custom Edition is currently in Version 1.0.9.620
You can download a demo version of Halo: Combat Evolved for free on the internet. There is also the Halo: Custom Edition, but this requires the CD Key of the full version of Halo: Combat Evolved installed on the computer you install Custom Edition on. Custom Edition is free, and allows for the use of user-created maps. It does not include the campaign though.
You can't cheat unless you have the Trial version of Halo Combat Evolved or you have the Halo Dev Trainer. You can also cheat on the edition to Halo Combat Evolved which is just a standalone version called Halo Custom Edition.*Please note that the cheats found online can only be used on the Halo Custom Edition and the Halo Combat Evolved Trial version. The retail version CAN NOT BE CHEATED on unless you have and are a modder.
Campaign, new game
Yes.
I pretty sure there is no 3rd player for halo campaign.
Another Spartan
Up to two players can play in the Co-Op Campaign mode on Halo: Combat Evolved.
yes bungie is now making a halo combat evolved remastered version and a halo 4 and on this one you can play xbox live again.
You can't, at least not on the Xbox version of the game. The PC version may be different.
Install setup files, and update to the newest version.
I would assume you install it.