In video gaming, a life is a play-turn that a player-character has, defined as the period between start and end of play. It is sometimes called a chance, particularly in all-ages games, to avoid the morbid insinuation of losing "lives". Generally, if the player loses all their health points, they lose a life. Losing all lives usually grants the player-character "game over", forcing them to either restart or stop playing.
The number of lives a player is granted varies per game type. A finite number of lives became a common feature in arcade games during the 1980s and mechanics such as checkpoints and power-ups made the managing of lives a more strategic experience for players over time. Lives give novice players more chances to learn the mechanics of a video game, while allowing more advanced players to take more risks.
Life (gaming) Wikipedia
Lives may have originated from the pinball mechanic of having a limited amount of balls. A finite number of lives (usually three) became a common feature in arcade games. Much like in pinball games, the player's goal was usually to score as many points as possible with their limited number of lives.
Later, checkpoints and saving allowed players that lost a life to continue the game at a specific point, rather than to start over. Refinements of health, defense and other attributes, as well as power-ups, made managing the player character's life a more strategic experience and made lost health less of the handicap it was in early arcade games.
It is common in action games for the player to have multiple lives and chances to earn more in-game. This way, a player can recover from making a disastrous mistake. Role-playing games and adventure games usually grant only one, but allow player-characters to reload a saved game.
Lives set up the situation where dying is not necessarily the end of the game, allowing the player to take risks they might not take otherwise. Multiple lives also allow novice players a chance to learn a game's mechanics before the game is over. Another reason to implement lives is that the ability to earn extra lives provide an additional reward incentive for the player.
The problem that may arise when a player loses their lives frequently is that it discourages the player from continuing the game fairly. If losing a life causes a loss of equipment, skills or points, a player may feel inclined to reset a game to its previous save point whenever they are losing a life.