How do I select different maps?

To play different maps and objectives you can use the Battle Portals located in the hub safe zones. You may also select different maps by opening the Pause Menu and selecting the Games tab. From there you will have the option to Create A New Game, Browse Games or Join With A Room Code.

When using the Browse Games function you may use the drop down filters to exclude hub maps, select the map you wish to play and select the difficulty mode for the rooms. If you hover over the game rooms you will see the players currently in the room and the mutators that may be active.