ODST style expansion pack

I was just thinking about areas where you see human allies in CE or CEA and thought about encounters where the chief wasn’t present to help. Where in cutscene it shows Captain Keyes looking for the weapons cache in the containment facility in 343 Guilty Spark. Other people have had similar ideas, but in Reach. Those ideas revolved around an ODST style game in the streets of New Alexandria, or where Sgt Buck went after you escort him during one of the side missions. My idea was what if there was some type of game that followed the story of the captain and marines when the master chief was not present. Either during the downing of the Pillar of Autumn, searching for the weapons cache on 343 Guilty Spark, or battles afterwards to see maybe how sgt johnson escaped, or what happened to Pvt Jenkins after being overrun in the containment facility. I know the part with Jenkins is better described already in one of the Novels, or graphic novels, but I think it would add a whole other dimension to the battle on Installation 04.

Ideas?