There would be a frigate or some other large UNSC ship and a Corvette or other Covenant ship in space and the objective is to render the enemy’s main ship destroyed by either blowing the other ship up from the inside (like how Noble Team did in Halo Reach’s campaign) or by destroying their engines or something along those lines. There could also be new vehicles and maps added to forge so people could make their own game modes like a seraph or space banshee or pelican for a few examples. Not expecting this to get added to the game but if someone from 343 industries or bungie Sees this and they end up adding to the game im not going to expect anything in return I’ll be happy enough just to know i came up with a great idea. Maybe a shout-out would be nice though 
I wouldn’t mind playing that, games like Star Wars: Battlefront 2 (2005) had a similar game mode and that was fun to play.