The Pacifist Challenge Run

A "Pacifist Run," also called a "Pacifist Challenge" is a playthrough of a game that normally involves violence and killing, but whose designers have given players the option of using non-violent strategies instead— often as a challenging alternative to the expected mode of play. Some games are designed so that players can choose to completely avoid killing and violent behavior altogether, while others provide the option to avoid only the majority of mandatory combat encounters.
Two Worlds I: Epic Edition is an example of a "pacifist run" RPG
Attempting "Pacifist Runs" through dangerous game worlds can be an enjoyable experience, due to the heightened challenge of narrowly escaping death at the hands of a multitude of foes and hazards. It also has a contrarian appeal in gaming situations where violence is the default solution, since "pacifist challengers" can try to defy the status quo by finding a way to win without using any form of violence— or at least without killing anything.
A pacifist run mage in Eschalon Book I casting a harmless "entangle" spell on some bandits.
There is no unifying factor among game players motivated to complete pacifist challenge runs though games, who have widely varying real-world philosophies.
Some are motivated by their personal nonviolent philosophies or a desire to have a more peaceful nonviolent gaming experience. Others see the pacifist run mainly as a strategic skill-testing exercise with no apparent philosophical or emotional attachment to minimizing violent behavior.
Others may be under pressure from outside parties, such as one pacifist gamer (featured in the Wall Street Journal's article "Videogamers Embark on Nonkilling Spree") whose mother initially would not allow him to play any games at all unless he was strapped to a treadmill, and later exerted efforts to ban him from playing any games rated above a "T" (Teen) rating. However, after discovering that her teen son had been recording Youtube videos of himself finding nonviolent ways to win otherwise violent games without actually killing anyone, she reportedly expressed approval. Married gamers who report difficulty reaching agreement about which exact games to play with their comparatively pacifistic spouses may also find non-violent or "zero-kill" runs an advantageous compromise.
A merchant from Two Worlds I comments on the benefits of having purchased a large crystal specimen from the protagonist, who acquired the crystal without using violence.
The Future of the Pacifist Run 

Violence in video games is unlikely to be phased out at any time in the foreseeable future, but as games continue to become more sophisticated and intense in their degree of realism, chances are excellent that the future of the "Pacifist Run" will be a bright one:
On the demand side: Veteran gamers bored with violent gameplay already find the pacifist run a refreshing challenge, while others who would ordinarily never buy violent games for various reasons suddenly become willing to spend their money on games that reportedly include the option of a pacifist challenge run.
From the developer's point-of-view, enabling a solid pacifist run isn't necessarily going to cost much extra, since the designers have usually already done most of the work necessary to enable a pacifist-run using their existing game engines: Many of the games that come close to being winnable via a perfect "zero kill run"—yet regrettably fall short by forcing the player to make a just a few mandatory "kills"— would often need only very minor adjustments (such as adding the ability for a player to open a locked door or passage) to enable nonviolent players to win without having to kill anything.
The pacifist challenge run has also been gaining more mainstream support in recent years, sometimes in some surprising places, in which some of the more violent games on the market also give players the option to win with little or no mandatory killing.