Marvel's Avengers Game: 10 Gameplay Details You Totally Missed
5. There Will Be A Main Hub World
As clarified by the developers in interviews, although the game will be separated into distinct mini open-worlds for players to explore, there'll always been one static hub world to jump back to. From here, you can launch into main and side missions as you see fit, as well as tinker with your characters and no doubt interact with other members of The Avengers.
Again, this kinda sounds like Marvel: Ultimate Alliance. In between missions in those games you could head back to base, play trivia games, interact with other characters and brush up on your training. It was a cool feature, and managed to imbue those titles with so much personality, as well as drawing attention to parts of the Marvel universe that wouldn't make sense in the actual story.
How extensive the hub is going to be and what you do there hasn't been revealed, but hopefully it's robust, and something you can customise the more the game goes on. Essentially, treat it like Mother Base from MGS V and you're good to go.