Shooter games (also known as 'shoot em up' games) are a sub-genre of action game, which often test the player's speed and reaction time. It includes many subgenres that have the commonality of focusing "on the actions of the avatar using some sort of weapon. Usually this weapon is a gun, or some other long-range weapon". A common resource found in many shooter games is ammunition. Most commonly, the purpose of a shooter game is to shoot opponents and proceed through missions without the player character dying.