While most Halo fans are currently eagerly awaiting the launch of Season 2: Lone Wolves for Halo Infinite, 343 Industries hasn't forgotten about Halo: The Master Chief Collection. After a troubled release, it has evolved through the years and could today be considered one of the best and most generous collections of all time.
A surprisingly big update with new content has been presented over at Halo Waypoint, with Flood Firefight for Halo 3: ODST as the main draw. It has seen several new upgrades as well to improve the mode, with one being "that Flood are accompanied by dense fog which gives each Firefight mission a new and spooky ambiance".. 343 Industries also explains that "Flood can now occupy vehicles for the first time since Halo 2", which sounds interesting. There's even a surprise thrown into the mix:
"Lastly, unlike the Master Chief, ODSTs can be infected and resurrected by the Flood. Beware, as you may have to fight your own resurrected allies—or even yourself!"
Other new things that has been added to Halo: The Master Chief Collection are UI improvements, Forge and Mod Tools have been enhanced, and campaign cross-play is implemented for Halo 3 and Halo 3: ODST. There are also other new stuff that you can check out at the link above.