Looking back at both Reach and ODST’s FF modes, you would probably notice that both modes made you play as apart of UNSC. Sure, there was this one game-type called versus where you could play as covenant but that was perhaps the worst game-type considering how unbalanced it was. So here I have a picture of this: Imagine you were a Zealot elite in the middle of you ship with one or two guards with (like Ultras or hunters I guess…) and slowly your ship is falling under the flood infection kind of like that in the truth and reconciliation or high charity. You can change your class of elite with the very limited respawns you have; each of which are different. Eventually you make it off your ship, but the battle continues, now opening a large terrain and usable vehicles at your disposal (don’t ask me how or why their there). There is pretty much no humans/UNSC involved just simple covenant vs. flood.
Also if you wondering I don’t want this to turn out like gears of wars’ “beast mode”; It should be more like the Quarantine zone from halo 2. I would assume this could be used also as an awesome DLC mode; your thoughts?