AFallout: New Vegasplayer beat the game on Hardcore mode without killing a single NPC. When developer Obsidian Entertainment was makingFallout: New Vegas, one of its core design tenets was to ensure that players could complete the main questline without killing anyone, if they so choose.

Fallout: New Vegas’ Hardcore mode is not a difficulty setting, but rather an entirely separate mode that doesn’t make enemies more difficult. It makes a few substantial changes to the way several of the game’s mechanics functionas players explore the expansive city of New Vegas. For instance, with Hardcore mode activated, stimpaks and Radaway no longer work instantly. Instead, they heal and eliminate radiation, respectively, over time. Additionally, the player must drink water, eat food, and get a good night’s sleep. Sleeping doesn’t help the player recover health, either.

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A hardcoreFallout: New Vegasplayer who goes by the name of TheMillionthOne in the game’s subreddit created a character named Michaela, a doctor who so strictly adheres to the Hippocratic Oath, especially its vow to abstain from all intentional wrong-doing and harm, that she refuses to kill any character in the game, including robots. TheMillionthOne gave Michaela three rules to live by: Michaela can’t kill, her companions can’t kill, and Michaela cannot trick an enemy into dying. 125 quests later, Michaela and TheMillionthOne did it. They unlocked one ofFallout: New Vegas’most difficult achievements to obtain, “Hardcore,” without having killed a single character.

One of the tricks TheMillionthOne used to pull off their impressive achievement was making sure to get the Robotics Expert perk, which let them turn off all machinery. The idea being that a killer robot that’s been turned off isn’t actually dead. It can still be turned on within the logic oftheNew Vegasin-game universe. TheMillionthOne cites the character Doctor Mobius as proof. The character has an army of robot scorpions at his disposal, including a giant robo-scorpion that can be turned off but will be turned back on moments later.

TheMillionthOne says that completing a no-kill run can go smoothly if the player sides with the right factions, along with making the right choices within faction questlines. TheMillionthOne also mentioned that it’s more difficult to keep up the no-kill ethos inFallout: New Vegas’ DLCs. While it’s still possible, there are a few moments, especially in theLonesome RoadDLC, where a player might have to get creative. Luckily, the developers at Obsidian made a game where player creativity is encouraged and rewarded. Now if they could only get the chance tomake anotherFalloutgame likeNew Vegas’ director wants.

Fallout: New Vegasis available now for PC, PS3, and Xbox 360.