This is easiest to do on Recruit difficulty and happens during the mission "Numbers", where you will meet Dr. Clarke and be ambushed by enemies. You must play this entire mission using only dual wield weapons. You cannot pick up or fire other weapons. You will start the mission with the "CZ75 Dual Wield" pistols. Once you have jumped the rooftop, they will move a fridge from the side of a wall to open a weapon stash. Inside in the middle of the wall you will find the "Kiparis Dual Wield" Sub Machine Guns. Many of the enemies have Kiparis so finding ammo while shooting them down should not be an issue, but keep your "CZ75 Dual Wield" pistols on hand. Pressing will fire the weapon in your left hand, and pressing will fire the weapon in your right hand. If you press , both weapons will be reloaded at the same time. During the mission, it is okay to melee/knife with or to kill enemies by throwing a grenade with .