Your mission in this online game is to control elite marines, save all survivors and bring them to evacuation point. Use WASD KEYS to move. Click the LEFT MOUSE BUTTON to shoot. Press the SPACEBAR to change weapon. Press "R" KEY to reload. Use "G" KEY to throw a grenade. While you will progress in the game story you will get additional items to build three types of traps. Go through in-game tutorial for more tips and tricks. Have fun!