So...due to 343 Industries being a fail of a company with config files and shit...this was found. I decided to poke the memory and it worked.
Features include:-
Mission Loading (Load any level you want)
All Skulls, All Terminals etc enabled
God Mode, Noclip, Screenshot, Free Cam, Third Person, First Person
Brightness/Gamma/Hue Settings
and many others.
Video by me.
Menu found by iBotPeaches with assistance from Xerax, Deadcanadian and AMD.