Many games, in particular open world games and RPG's, feature a reputation system which can adjust the game world to fit the character of the player. For example, the responses of NPC's to the player, the weapons or abilities the player unlocks or even the ending can be directed by the actions and choices or the player character. Reputation systems are particularly popular with RPG developers, with popular RPG series such as Megami Tensei, SaGa, Fallout and Mass Effect featuring them prominently, utilizing systems that can significantly adjust the player's experience depending on their moral choices. Some series, such as Megami Tensei, Ogre, Final Fantasy XI, World of Warcraft, or Grand Theft Auto, have multiple factions the player can choose to side with. By helping or opposing a faction the player accrues a type of reputation, which affects the way the faction reacts to the player and can open or close missions. Often games, in particular MMO's, have region specific reputations. For example, in World of Warcraft players receive various benefits such as vendor discounts for becoming honored in a region.
Elder Scrolls IV: Oblivion
Oblivion utilizes the progression of reputation in a dualistic fashion for progression through the game. 1) As part of the major side-questing system the player in encouraged to join multiple factions throughout the land, such factions include the Fighter's Guild, the Mage's Guild, the assassin's society known as the Dark Brotherhood, and several others. While accomplishing tasks for these groups allows for an increased reputation within the group, and by extension progression through their ranks, the same actions can, on occasion, cause negative reputation to incur against other groups. 2) Also part of the overall experience is a fame/infamy system, the which is greatly affected by progression through the distinct factions in the game. Such increase and decrease of fame (or infamy) can have a drastic effect on the ability of the player to heal and purge diseases via chapel altars, gain information from NPCs, gain certain quests and even join some of the guilds.
EverQuest features hundreds if not thousands of different factions within the world of Norrath. A player's faction standing with any particular group will often determine whether a particular NPC will attack on site, offer specific quests, give discounts on goods purchased, or even speak to them at all. Every city is likely to have separate faction for things such as the city guards, the different guild halls ( classes), and merchants. A player may be loved by monk guild in Freeport, but if that monk has killed a few of the guards at the tollbooth in West Commonlands, the Freeport Militia aren't going to tolerate that monk being within the city's walls. Faction can be earned through questing or by simply killing members of the opposing faction. Some classes have ways of avoiding faction detection, such as rogues who can sneak behind merchants who despise them and still buy/sell goods. Enchanters can use illusion spells to make themselves appear as though they belong to a certain faction (i.e. a High Elf enchanter using a Dark Elf illusion to enter Neriak). A player's choice of religion during character creation can often influence their faction as well, which is why most enchanters decide to be agnostic. Players can often safely check their faction standing from a distance by conning an NPC of said faction. The levels of reaction include ready to attack, threatening, dubious, apprehensive, indifferent, amiable, kindly, warmly, and ally.
The Fallout games use a Karma system which changes the way various types of NPC's react to the player character depending on the players actions and moral choices. There are five levels of Karma: Very Evil, Evil, Neutral, Good and Very Good, and the player begins neutral. By getting to certain levels the player attains skill bonuses and titles. The system is very cause and effect, for example if the player kills somebody they lose Karma, gaining them respect from bad characters in the game such as slavers, but losing them respect from good characters such as the sheriff. If the players Karma gets to a certain level in either direction, positive or negative, they will be targeted by mercenaries or bounty hunters respectively. The Karma system was called the 'Reputation' system in the original Fallout, but was changed to Karma for the second and third games.
Grand Theft Auto
Several games in the Grand Theft Auto franchise feature multiple gangs. Carrying out missions for each gang results in them being more friendly to the player. However, this can also mean that rivaling gangs are more likely to attack the player if they stray into the wrong area of the game world. With Grand Theft Auto IV this is changed into the way specific characters perceive the player; by going out to social events with certain characters, they grow more fond of the player. This leads to them providing specific gameplay perks.
The concept of reputation is so core to inFAMOUS's gameplay that it features in the title of the game itself. The player can either carry out good (Heroic) or bad (Infamous) actions. These actions build up points in a binary karma system that change the way characters in the game react to the player, affect which powers the player unlocks, the way the player character looks, and even affects the ending.
World of Warcraft
In World of Warcraft, reputation can be gained with several different factions. It can be gained by killing certain types of enemies or completing quests for specific factions but, in some cases, it can also be lost by killing the faction's non-player characters or by helping a rivaling faction. The more reputation the player has with a certain faction, the more specific rewards are available for the player to purchase.