Fallout Series: Post apolcalyptic pacifist run RPGs

The Fallout game series is one we may never have discovered if it hadn't been for recommendations by other "pacifist challenge" gamers: Violent post-apocalyptic wastelands simply hadn't occurred to any of us as places to look for good pacifist run games. Apparently, however, most games in the Fallout series are versatile RPGs that allow players enough freedom of choice to also make excellent pacifist challenge runs with very few kills at minimum, with at least one of the games (Fallout 4) being a full zero kill run. The series also has a reputation for having a good sense of humor, despite the dystopian setting.
Fallout 4: A confirmed zero kill run RPG...
The setting of the first Fallout game is Southern California following a nuclear apocalypse, and Wikipedia describes the premise this way: "The protagonist, referred to as the Vault Dweller, is tasked with recovering a water chip in the Wasteland to replace the broken one in their underground shelter home, Vault 13. Afterwards, the Vault Dweller must thwart the plans of a group of mutants, led by a grotesque entity named the Master."
Screenshot from Fallout 1
The games reportedly allow you to approach and win using an impressive range of player characters and occupations, and enabling a "pacifist run" is a tradition in the series. We don't know yet exactly what the "kill" standard is in Fallout 1 and 2 (i.e., how few entities you can actually bypass without dispatching and still win), but G.W. Trevelyan will be finding out soon, since he recently bought the first Fallout game on Steam and has his eye on the others too...
Screenshot from Fallout 1
The other games in the Fallout series reputedly also achieve a high standard in allowing players to avoid killing things. According to the article "15 Violent Games You Can Beat Without Killing Anyone":

Fallout 3 apparently allows players to complete the main quest and many side-missions without killing anything except a "radroach" (roach mutated by radioactivity) in the in-game tutorial.

Fallout: New Vegas is said to have only one obstacle to being a bona fide zero-kill run, in which a boss (I think the final villain) has to be dispatched in some way or other to win the game.
Fallout: New Vegas
Fallout 4 apparently does even better, and can be completed as a complete zero kill run. (As it happens, at the time we wrote this Fallout 4 also topped the list of our internet search results for "zero kill run," even without any other Fallout-related keywords included in that search.) Intriguingly, it sounds like one of the ways to avoid kills in some of the Fallout series games is by building a character with persuasion skills that impact NPC reactions to the player, which sounds like it might be a lot of fun.
The Fallout Series: One of many "contrarian" franchises where you might not expect to find a pacifist run...
As for Fallout 1: The game's skill and attribute system looks very promising. A sampling of the available skills include Sneak, Lockpick, Steal, Science, Repair, Speech, Barter, Gambling, and Outdoorsman, all stimulating the imagination with an array of interesting nonviolent possibilities, which we're planning to test out soon...
Another screenshot from the original classic CRPG: Fallout 1