Light-gun shooter, also called light-gun game or simply gun game, is a shooter video game genre in which the primary design element is to simulate a shooting gallery by having the player aiming and discharging a gun-shaped controller at a screen. Light-gun shooters revolve around the protagonist shooting virtual targets, either antagonists or inanimate objects, and generally feature action or horror themes and some may employ a humorous, parodic treatment of these conventions. These games typically feature "on-rails" movement, which gives the player control only over aiming; the protagonist's other movements are determined by the game. Games featuring this device are sometimes termed "rail shooters", though this term is also applied to games of other genres in which "on-rails" movement is a feature. Some, particularly later, games give the player greater control over movement and in still others the protagonist does not move at all. On home computer conversions of light-gun shooters, mouse has been often an optional or non-optional replacement for a light gun.

Light-gun shooters typically employ "light gun" controllers, so named because they function through the use of light sensors. However, not all "light-gun shooters" use optical light guns, but some may also use alternative pointing devices such as positional guns or motion controllers. Mechanical games using light guns had existed since the 1930s, though they operated differently from those used in video games. Throughout the 1970s mechanical games were replaced by electronic video games and in the 1980s popular light-gun shooters such as Duck Hunt emerged. The genre was most popular in the 1990s, subsequent to the release of Virtua Cop, the formula of which was later improved upon by Time Crisis. The genre is less popular in the new millennium, as well as being hampered by compatibility issues, but retains a niche appeal for fans of "old school" gameplay.

"Light-gun shooters", "light-gun games" or "gun games" are games in which the protagonist shoots at targets, whether antagonists or objects, and which use a gun-shaped controller (termed a "light gun") with which the player aims. While light-gun games may feature a first-person perspective, they are distinct from first-person shooters, which use more conventional input devices. Light-gun games which feature "on-rails" movement are sometimes termed "rail shooters", though this term is also applied to other types of shooters featuring similar movement. The light gun itself is so termed because it functions through the use of a light sensor: pulling the trigger allows it to detect light from the on-screen targets.

Targets in light-gun shooters may be threatening antagonists such as criminals, terrorists or zombies, or they may be inanimate objects such as apples or bottles. Although these games may be played without a light gun, the use of more conventional input methods has been deemed inferior. Light-gun shooters typically feature generic action or horror themes, though some later games employ more humorous, self-referential styles.

Light-gun shooters primarily revolve around shooting large numbers of enemies attacking in waves. The protagonist may be required to defend themself by taking cover, or by shooting incoming thrown weapons, such as axes or grenades. The player may also compete against the clock, however, with some games also featuring boss battles. Games may also reward the player for accurate shooting, with extra points, power-ups or secrets. Games which do not pit the player against antagonists instead feature elaborate challenges constructed mainly from inanimate objects, testing the player's speed and accuracy. More conventional games may feature these types of challenges as minigames.

Light-gun shooters typically feature "on-rails" movement, which gives the player no control over the direction the protagonist moves in; the player only has control over aiming and shooting. Some games, however, may allow the protagonist to take cover at the push of a button. Other games may eschew on-rails movement altogether and allow the player to move the protagonist freely around the game's environment; still others may feature a static environment. Light-gun shooters use a first-person perspective for aiming, though some games may allow the player to switch to a third person perspective in order to maneuver the protagonist.

Gun games had existed in arcades before the emergence of electronic video games. Shooting gallery carnival games date back to the late 19th century. Mechanical gun games first appeared in England's amusement arcades around the turn of the 20th century, and before appearing in America by the 1920s. The British "cinematic shooting gallery" game Life Targets (1912) was a mechanical interactive film game where players shot at a cinema screen displaying film footage of targets.

The first light guns appeared in the 1930s, with the Seeburg Ray-O-Lite. Games using this toy rifle were mechanical and the rifle fired beams of light at targets wired with sensors. A later gun game from Seeburg Corporation, Shoot the Bear (1949), introduced the use of mechanical sound effects. By the 1960s, mechanical gun games had evolved into shooting electro-mechanical games. A popular sophisticated example was Periscope (1965) by Namco and Sega, with other examples including Captain Kid Rifle (1966) by Midway Manufacturing and Arctic Gun (1967) by Williams. The use of a mounted gun dates back to a Midway mechanical game in the 1960s.