The player can select from four difficulty levels: Walk on the Beach, Combat Op, Suicide Mission, and the hardest difficulty, FUBAR, which is only unlocked after completing the game on Suicide Mission.[1] Various new weapons and equipment become available as the game progresses, some dropped by downed enemies.[2] These include several different rifles, handguns, and machine guns.[3] Some offer alternate firing modes, like attaching a suppressor or using a telescopic sight.[4] Players can also acquire and make use of grenade launchers, hand grenades, and rocket launchers.[5] However, the player can only carry two weapons at a time.[6] Supply caches can be found in different parts of the game, allowing the player to refill their ammo and grenades.[7] Whenever the player successfully shoots an enemy in the head, the game enters a slow-motion mode for a short period of time. The player can also defeat enemies at close range via melee combat. Dying enemies can be executed, which grants the player additional ammo.[8] Hiding behind cover can provide protection and prevents the player from being shot, as well as providing opportunities to blindfire or lean out to shoot enemies.[9]