After you install the game to start the game you need to select the degree of difficulty. "rookie" is the easiest enemy in one shot can kill, "veteran" medium difficulty, and the enemy will die with 2 shots, "hardcore" is the most difficult and the enemy will die with 3 shots. Difficulty After selecting "I Accept" click and conflict begins. During the conflict "1" key if you press the desert eagle, "2" key with the M4 rifle, "Q" key will remove the sniper. Shells are finished with "R" button and magazine change. "F" with a flash grenade at the enemy so you'll be a short blind and you can not attack. "E" If you press the button to go through the trenches and nobody can hit you.