Ghost Recon Wildlands (2017) supported unbounded online co-op, free roam or mission joined, across the ENTIRE 24km x 24km open world. 343i can do better. : r/halo
Multiplayer - Tom Clancy's Ghost Recon: Wildlands | Interface In Game
Tom Clancy's Ghost Recon Breakpoint (UK) | Xbox One | CDKeys
Ghost Recon: Frontline Features 100-Player Online Matches | Digital Trends