Hostile machines are invading trying to destroy your portal which you have to defend no matter what. Control your robot and demolish those Effing Machines. Each machine you destroy rewards you with metal which you can use in between levels to upgrade your weapon to deal more damage, repair yourself, buy turret or to start completing your Emp. You need 4 parts of Emp to complete it, after you do so you will put a permanent stop to machine invasion and become the hero of your city. Now start playing and show them who's the boss.