Halo 1 and 2 4 player Coop

Halo PC Custom Edition on 2-4 player split-screen guide : r/localmultiplayergames

343 discusses if it's possible to add 4-player co-op to Halo and Halo 2

Halo Origins Bundle - Xbox 360 : Video Games

The Making of Halo: How Combat Evolved from Blam! Part 2, by Andrew G.

Halo 4: Splitscreen Multiplayer Gameplay - How to Unlock Not Some Recruit Anymore Achievement

Halo Infinite Campaign Co-Op, Forge Beta, And More Arrive In November - Game Informer

The best Halo games, ranked by campaign and multiplayer - The Washington Post

4-Player Co-op Glitch, Halo Alpha

Co-Optimus - FAQ - Halo 4 Co-Op FAQ