The mech is one vehicle, they're just showcasing it since no games have mechs anymore. There's all sorts of vehicles and weapons just like any other BF game. The only difference is that they're not restricted by modern technology anymore.
The setting is interesting, it takes place during a new ice age whe only the area around the equator can grow food anymore. So the EU, Pan Asia, and the Americas are fighting over it. Can someone say resource war?