Anthem is not your traditional MMO. It is a shared RPG that you and your teammate trek out for adventure in a new world. You and your friends will experience the same things in the open world. Fort Tarsis is where a player defines their own world. Every action impacts Fort Tarsis. Fort Tarsis is player specific and is not the open world. You will have a crew that stays with you no matter if you are in open world or in Fort Tarsis. Anthem is set to release 02/22/2019.
For more information go to https://www.ea.com/games/anthem.