Use Moue or Touch the screen. Follow the in-game tutorial. You must defend your position against revolutionaries and renegades.
Lead your team to the final victory. You have a tons of different weapons available: gun, machine gun, bazooka, rifle, sniper rifle, kalashnikov, flame thrower, rocket launcher, heavy weapons, shotgun, the big bertha, bombs, barbed wire, mines, sandbags, defense's turret ... and so many more