From the earliest games in the 1970s onward, game platform hardware and memory improved, which led to bigger and more complex computer games, which, in turn, tended to take more and more time to play them from start to finish. This naturally led to the need to store in some way the progress, and how to handle the case where the player received a "Game over". More modern games with a heavier emphasis on story telling are designed to allow the player many choices that impact the story in a profound way later on, and some game designers do not want to allow more than one save game so that the experience will always be "fresh".
Game designers allow players to prevent the loss of progress in the game (as might happen after a game over). Games designed this way encourage players to 'try things out', and on regretting a choice, continue from an earlier point on.
Although the feature of save games often allows for gameplay to resume after a game over, a notable exception is in games where save games are deleted when it is game over. Several names are used to describe this feature, including "permadeath", "iron man", and "hardcore", and the feature has developed over the years from being the only kind of save system per game to the more modern 'suspend game' feature among regular save points. For online games the game's progress is maintained on the remote server. In some games, upon resuming the game from a save game, the software locks or marks the save game. Early examples include Moria and Diablo II's "hardcore" mode where the character save game is managed by the battle.net server. Depending on the game the feature may be feasible or not, depending on how the game handles interrupting or ending a game session.
The use of saved games is very common in modern video games, particularly in role-playing video games, which are usually much too long to finish in a single session.
History and overview
In early video games, there was no need for saving games, since these games usually had no actual plot to develop and were generally very short in length.
The relative complexity and inconvenience of storing game state information on early home computers (and the fact that early video game consoles had no non-volatile data storage) meant that initially game saves were represented as "passwords" (often strings of characters that encoded the game state) that players could write down and later input into the game when resuming.
BYTE magazine stated in 1981, regarding the computer text adventure Zork I's save game feature, that "While some cowards use it to retain their hard-earned position in the game before making some dangerous move", it was intended to let players play over many weeks. Home computers in the early 1980s had the advantage of using external media for saving, with compact cassettes and floppy disks, before finally using internal hard drives.
On later cartridge-based console games, such as Kirby's Adventure and The Legend of Zelda, saved games were stored in battery-backed RAM on the game cartridge itself. In recent consoles, which use disc-based media for storing games, saved games are stored in other ways, such as by use of memory cards or internal hard drives on the game machine itself.
Some games do not save the player's progress towards completing the game, but rather high scores, custom settings, and other features. The first game to save the player's score was Taito's seminal 1978 shoot 'em up title Space Invaders.
Depending on the game, a player will have the ability to save the game either at any arbitrary point (usually when the game has been paused), after a specific task has been completed (such as at the end of a level), or at designated areas within the game known as save points.
The available ways to save a game affect gameplay, and can represent a practice of players or an explicit decision by designers to give the game a particular feel or alter its difficulty.
Time and location of saving
A video game may allow the user to save at any point of the game, any time, though using it too much may be seen by some as cheating and in such a context referred to as save scumming. There are modified versions of this, too. For example, in the GameCube game Eternal Darkness, the player can save almost anytime, if an enemy is not in the room. To make gaming more engaging, some video games may impose a limit on the number of times a player saves the game. For instance, IGI 2 allows only a handful saves in each mission; Max Payne 2 imposes this restriction on the highest level of difficulty.
Some video games only allow the game to be saved at predetermined points in the game, called save points. (Not to be confused by "checkpoints".) Save points are employed either because the game is too complex to allow saving at any given point or to make gaming more engaging by forcing the player to rely on skills instead of on the ability to retry indefinitely. Save points are also far easier to program, so when a game developer has to rush a game, save points are attractive to develop.
Some games use a hybrid system where both save anywhere and save points are used. For example, Final Fantasy VII permits saving anywhere when the player is traveling on the world map, but once the player enters a location (e.g. town, cavern or forest), saving is only possible on save points. Additionally, there is one location (called the Northern Crater) in which the player is allowed to deploy one save point in a spot of choice.
Types of saved games
Game saving does not need to be manual. Some video games save the game in progress automatically, such as at the start of each level, after the pass of a fixed amount of time (if saving anywhere is allowed) or at certain predetermined points in the game (an extension to save point concept).
Some games only permit suspend saves in which the game is automatically saved upon exiting and reloaded upon restarting. The aim of a suspend save is only to allow the gameplay to be temporarily interrupted; as such, suspend saves are erased when the player resumes the game. The act of copying and reusing suspend save files is a form of cheating.
Checkpoints are locations in a video game where a player character respawns after death. Characters generally respawn at the last checkpoint that they have reached. A respawn is most often due to the death of the in-game character, but it can also be caused by the failure to meet an objective required to advance in the game. Checkpoints might be temporary, as they stop working when the character loses all of its lives. Most modern games, however, save the game to memory at these points, known as auto-saving.
Checkpoints might be visible or invisible to the player. Visible checkpoints might give a player a sense of security when activated, but in turn sacrifice some immersion, as checkpoints are intrinsically "gamey" and might even need an explanation of how they work. Invisible checkpoints do not break immersion, but make players unsure of where they will respawn. Usually, if a player does get a game over, then their progress will be lost, and the player would lose all of their checkpoints. 
Quick saving and quick loading allow the player to save or load the game with a single keystroke. These terms are used to differentiate between the traditional saving mechanism where the player is required to invoke a menu or dialog box, issue save order, specify a title for the game being saved and, if applicable, confirm whether an old saved game file with same title should be overwritten. The term "quick save" may be used in video games that lack the traditional saving mechanism altogether.
The advantage of quick saving is its low burden: The player only has to press a button and, if applicable, wait a few seconds. The disadvantage is the automatic loss of the previous quick-saved game. Games that only offer quick saving may be impossible to play by two different players (or more) unless there is a mechanism to distinguish players, such as user accounts.
Passwords are a form of saved game not stored on non-volatile memory. Instead, everything needed to reconstruct the game state is encoded in a string of text (the password) and displayed to the player, who can then record or memorize it. The player may later resume play from that point by entering the same password. Passwords are only feasible when the amount of data being saved is only a few bytes.
A save state is a form of saved game in emulators. A save state is generated when the emulator stores the contents of random-access memory of an emulated program to disk. Save states enable players to save their games even when the emulated game or system does not support the feature; this is commonly associated with cheating. For instance, save states may be used to circumvent saving restrictions or to abuse RNG. An associated concept is save state hacking, the practice of altering the save states to alter gameplay conditions, usually in favor of the player. Save states are comparable to snapshots in hardware virtualization or hibernation in computing, with save states being a limited form of snapshots.
Save states have started to receive mainstream usage in the early 2010s with Nintendo's Virtual Console. Some Wii U and 3DS Virtual Console titles allow players to save a restore point, which is like a quick save but has no restrictions on reloading. Although likely derived from quick saves, restore points are functionally identical to save states, and can be used for many of the same purposes.
Game designers often attempt to integrate the save points into the style of the game using skeuomorphism. Resident Evil represents save points with old fashioned typewriters (which require an ink ribbon item for each save), the Grand Theft Auto series used representations appropriate to the era of the setting: audio cassettes for the mid-1980s (Grand Theft Auto: Vice City), 3½-inch disks for the early-1990s (Grand Theft Auto: San Andreas), and compact discs for the late-1990s (Grand Theft Auto: Liberty City Stories). Many RPGs integrate saving into the form of a journal that the characters write into, or auto-save whenever the character stays at an inn or other resting place. Undertale implements the save game feature into the story of the game, saying that the player's ability to save is based on their "determination".
Although save points are typically seen as boons, some games have traps which use this tendency to fool the player. In Chrono Trigger, attempting to use fake save point in Magus's castle can actually bring the party into battle. In I Wanna Be The Guy, one save point is actually an enemy in disguise.
Some games employ limits to saving in order to prevent players from using them as a primary means of succeeding in the game. In Tomb Raider save points are consumed upon use, Donkey Kong Country 2: Diddy's Kong Quest charges two banana coins to use a save point more than once, and in Resident Evil the player must find and expend an ink ribbon for each save.
Another way saved games interact with each other is through passing along data to sequels. A famous example of this is the first three installments of the Wizardry series. To play the second and third installments, players needed to import the characters they'd used in the previous installment, which retained all experience and equipment gained in that installment. Later versions of the games made this feature optional, as do franchises such as the Fire Emblem, Shenmue and .hack series. Video games may also take the saved games of other video games into account; for example, the character Rosalina becomes available on Mario Kart Wii if there is a Super Mario Galaxy save on the console.
For many years, sharing game saves among friends has been very common. From trading passwords to swapping memory cards, gamers have always been able to help each other out to unlock features in a game. With the growing popularity of the Internet, many people upload their game saves to help out their online friends. However, with the inclusion of a progress meter or "gamerscore" that tracks player progress in games for the Xbox 360, many players are beginning to view those who load other people's files onto their systems as "cheaters". Some games such as Grand Theft Auto IV prevent the use of saved games made by other users. The Legend of Zelda: Oracles actually encourages this with a password swapping side quest that is available after finishing the main story.
Saved games have generally been rare at arcades, but have found some use, notably in the Konami e-Amusement system, or by the use of PlayStation cards, as in Dance Dance Revolution. These generally use either a magnetic card to store the data, or network (internet) connection, or some combination thereof. Similarly, passwords have generally been rare at arcades, with occasional exceptions, such as Gauntlet Legends.
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