Action game

The action game is a video game genre that emphasizes physical challenges, including hand–eye coordination and reaction-time. The genre includes diverse subgenres such as fighting games, shooter games and platform games which are widely considered the most important action games, though some real-time strategy games are also considered to be action games.

In an action game, the player typically controls the avatar of a protagonist. The avatar must navigate a level, collecting objects, avoiding obstacles, and battling enemies with various attacks. At the end of a level or group of levels, the player must often defeat a large boss enemy that is larger and more challenging than other enemies. Enemy attacks and obstacles deplete the avatar's health and lives, and the game is over when the player runs out of lives. Alternatively, the player wins the game by finishing a sequence of levels. But many action games are unbeatable and have an indefinite number of levels, and the player's only goal is to maximize their score by collecting objects and defeating enemies.

Defining elements
The action genre includes any game where the majority of challenges are physical tests of skill. Action games can sometimes incorporate other challenges such as races, puzzles, or collecting objects, but they are not central to the genre. Players may also encounter tactical and exploration challenges, but these games first-and-foremost require high reaction speed and good hand–eye coordination. The player is often under time pressure, and there is not enough time for complex strategic planning. In general, faster action games are more challenging. Action games may sometimes involve puzzle solving, but they are usually quite simple because the player is under immense time pressure.

Levels
Players advance through an action game by completing a series of levels. Levels are often grouped by theme, with similar graphics and enemies. Each level involves a variety of challenges, whether dancing in a dance game or shooting things in a shooter, which the player must overcome to win the game. Older games force players to restart a level after dying, although action games evolved to offer saved games and checkpoints to allow the player to restart partway through a level. Increasingly, though, some games allow for 'resurrection' or 'cloning' and the opportunity to regain lost items upon death for a certain sum of ingame currency, typically increasing exponentially the more times the player dies. The obstacles and enemies in a level do not usually vary between play sessions, allowing players to learn by trial and error. However, levels sometimes add an element of randomness, such as an enemy that randomly appears or that takes an unpredictable path.

Levels in an action game may be linear or nonlinear, and sometimes include shortcuts. For levels that require exploration, the player may need to search for a level exit that is hidden or guarded by enemies. Such levels can also contain secrets—hidden or hard-to-reach objects or places that contain something valuable. The prize can be a bonus (see below) or a non-standard exit that allows a player to access a hidden level, or jump ahead several levels. Action games sometimes offer a teleporter that will cause the player's avatar to re-appear somewhere else in the same level. Levels often make use of locked doors that can only be opened with a specific key found somewhere else in the level.

Action games sometimes make use of time restrictions to increase the challenge. However, game levels typically do not react to time passing, and day/night cycles are rare. When the timer expires, the player typically loses a life, although some games generate a difficult enemy or challenge. If the level is completed with time remaining, this usually adds to the player's score.

Character abilities
In most action games, the player controls a single avatar as the protagonist. The avatar has the ability to navigate and maneuver, and often collects or manipulates objects. They have a range of defenses and attacks, such as shooting or punching. Many action games make use of a powerful attack that destroys all enemies within a limited range, but this attack is rare.

Players may find a power-up within the game world that grants temporary or permanent improvements to their abilities. For example, the avatar may gain an increase in speed, more powerful attacks, or a temporary shield from attacks. Some action games even allow players to spend upgrade points on the power ups of their choice. In action games, most of the avatar's character development comes from power-ups and new moves, and mental states do not usually change or progress.

Obstacles and enemies
In action games that involve navigating a space, players will encounter obstacles, traps, and enemies. Enemies typically follow fixed patterns and attack the player, although newer action games may make use of more complex artificial intelligence to pursue the player. Enemies sometimes appears in groups or waves, with enemies increasing in strength and number until the end of the level. Enemies may also appear out of thin air. This can involve an invisible spawn point, or a visible generator which can be destroyed by the player. These points may generate enemies indefinitely, or only up to a certain number. At the end of a level or group of themed levels, players often encounter a boss. This boss enemy will often resemble a larger or more difficult version of a regular enemy. A boss may require a special weapon or attack method, such as striking when the boss opens their mouth or attacking particular part of the Boss.

Health and lives
In many action games, the avatar has a certain amount of hitpoints or health, which are depleted by enemy attacks and other hazards. Sometimes health can be replenished by collecting an in-game object. When the player runs out of health, the player dies. The player's avatar is often given a small number of chances to retry after death, typically referred to as lives. Upon beginning a new life, the player resumes the game either from the same location they died, a checkpoint, or the start of the level. Upon starting a new life, the avatar is typically invincible for a few seconds to allow the player to re-orient themselves. Players may earn extra lives by reaching a certain score or by finding an in-game object. Arcade games still limit the number of player lives, while home video games have shifted increasingly to unlimited lives.

Graphics and interface
Action games take place in either 2D or 3D from a variety of perspectives. 2D action games typically use a side view or top-down view. The screen frequently scrolls as the player explores the level, although many games scroll through the level automatically to push the player forward. In 3D action games, the perspective is usually tied to the avatar from a first-person or third-person perspective. However, some 3D games offer a context-sensitive perspective that is controlled by an artificial intelligence camera. Most of what the player needs to know is contained within a single screen, although action games frequently make use of a heads-up display that display important information such as health or ammunition. Action games sometimes make use of maps which can be accessed during lulls in action, or a mini-map that is always visible.

Scoring and victory
Action games tend to set simple goals, and reaching them is obvious. A common goal is to defeat the end-of-game boss. This is often presented in the form of a structured story, with a happy ending upon winning the game. In some games, the goal changes as the player reveals more of the story.

Many action games keep track of the player's score. Points are awarded for completing certain challenges, or defeating certain enemies. Skillful play is often rewarded with point multipliers, such as in Pac-Man where each ghost that the avatar eats will generate twice as many points as the last. Sometimes action games will offer bonus objects that increase the player's score. There is no penalty for failing to collect them, although these bonus objects may unlock hidden levels or special events. In many action games, achieving a high score is the only goal, and levels increase in difficulty until the player loses. Arcade games are more likely to be unbeatable, as they make their money by forcing the player to lose the game. On the other hand, games sold at home are more likely to have discrete victory conditions, since a publisher wants the player to purchase another game when they are done.

Subgenres
Action games have several major subgenres. However, there are many action games without any clear subgenre, such as Frogger, as well as other types of genres like Adventure or Strategy that have action elements.

Beat 'em ups are games that involve fighting through a side-scrolling stage of multiple adversaries, using martial arts or other close-range fighting techniques.

Fighting games feature combat between pairs of fighters, usually using martial arts moves. Actions are limited to various attacks and defenses, and matches end when a fighter's health is reduced to zero. They often make use of special moves and combos. There are both 2D and 3D fighting games, but most 3D fighting games largely take place in a 2D plane and occasionally include side-stepping. They are distinct from sports games such as boxing games which attempt to model movements and techniques more realistically.

Maze games such as Pac-Man involve navigating a maze to avoid or chase adversaries.

Platform games involve jumping between platforms of different heights, while battling enemies and avoiding obstacles. Physics are often unrealistic, and game levels are often vertically exaggerated. They exist in both 2D and 3D forms.

Rhythm action games challenge the player's sense of rhythm, and award points for accurately pressing certain buttons in sync with a musical beat. This is a relatively new subgenre of action game. Rhythm games are sometimes classified as a type of music game.

Shooter games allow the player to take action at a distance using a ranged weapon, challenging them to aim with accuracy. Although shooting is usually a form of violence, non-violent shooters exist as well. This subgenre includes first-person shooters and third-person shooters, as well as a plethora of other shoot 'em up games taking place from a top-down or side-view perspective.

Physical impact
Studies have shown that people can improve their eyesight by playing action video games. Tests by scientists at the University of Rochester on college students showed that over a period of a month, performance in eye examinations improved by about 20% in those playing Unreal Tournament compared to those playing Tetris. Most arcade games are action games, because they can be difficult for unskilled players, and thus make more money quickly.

Researchers from Helsinki School of Economics have shown that people playing a first-person shooter might secretly enjoy that their character gets killed in the game, although their expressions might show the contrary. The game used in the study was James Bond 007: Nightfire.

History
A major turning point for action games came with the 1978 release of the shoot 'em up game Space Invaders, which marked the beginning of the golden age of arcade video games. As a result of Space Invaders' mainstream success, the industry came to be dominated by action games, which have remained the most dominant genre in video arcades and on game consoles through to the present day. Along with Space Invaders, Asteroids from 1979 and Pac-Man from 1980 have also become iconic examples from the action genre. Robotron: 2084, released in arcades in 1982, also became a classic in the shooter subgenre.

In much the same way Space Invaders set the template for the shooter game subgenre, Donkey Kong did the same for the platform game subgenre when it released in 1981. That same year saw the emergence of martial arts themed games, with Karate Champ establishing the one-on-one fighting game subgenre, and Kung-Fu Master laying the foundations for the side-scrolling beat 'em up subgenre.