This one is a bit of an experiment really. I'm not sure if anything like this has been done before, and if it hasn't, maybe there is a very good reason for it. On these maps, one team starts in the very middle of the map, while the other team starts far from each other, but surrounding the players in the middle.
Some maps use completely normal resources while other maps experiment with unequal resources for the players.
Because of this setup, the maps are only recommended to be played in a 4v4 format - while you can get some decent games from 2v2 matches, some of the maps are not yet fully optimized for this. If you choose to do this, I recommend still playing the map on an 8-player map size.
To change which team is defending/attacking, simply tick or untick the "Teams Together" button in the in-game lobby.
Feedback is always appreciated, but especially valued in this case. Don't hesitate to post any suggestions as things might not work as I originally intended.