Halo 6 of course…So the John/Locke/Cortana one
I think that Halo 6 should continue with the story thats been going on so far. But I chose open world because that would also be a good game to see in the future. It would be like an MMO FPS. Warhammer 40k is working on something like that and I think it could work with the Halo universe.