Desert Rifle 2 - Enroll for an elite marksman mission deep into enemy territory. Mouse to aim / shoot. Lower mouse to take cover. R to reload. Q/E to switch weapons up and down. 1-7 to explode mines or click trigger icons. Space bar to use optical sight. Hold X to fire grenades (M4 and XM rifles only). M to switch fire mode (selective fire rifles only). P to pause game.