Halo 2 DID have some cut content that was fun to add back into the game. Also replacing all the marines with grunts and all the grunts with "cyborg" aka chief. was damn near perfect.
"Halo 2: Grunt revenge". Sadly it wasn't open to everything being changed because if you tried say, switching the chief with something else the game would bug out and stop working. Xbox literally was a computer so if the game bugged out you had to force restart.