Some new campaign information about Halo 5 may have been leaked thanks to NeoGAF. According to a forum post, Halo 5 will be open-world, and Master Chief will be able to explore six to eight planets in the campaign.
Each of the levels will have their own set of main missions and side missions, and with these new additions, the sequel could potentially be up to five times bigger than the story of the previous Halo.
Keep in mind there has not been any official story details regarding the next halo game from Microsoft. The only thing they have confirmed is that the game will run at 60 frames per second on the Xbox One and will have dedicated servers.
Check back for more Halo 5 information in the future.