I wouldn't say its the most evil thing I've ever done in game buuuuuuuut its probably the one you want to hear.
SO Long story concluded the most evil or more accurately horrific thing I've done is splatter/ dismember every citizen of Megaton float their heads in the centre of town around the atomic bomb, wait until night, then set them all on fire and watch the city twinkle to life as a bunch of little fires start everywhere.
Funnily enough this isn't my usual play style and I was always reload the game to a point before(seriously who doesn't want Megaton over Tenpenny)usually I have difficulty playing the 'evil' character. Did't steal in Skyrim full paragon in Mass Effect and a generally nice dude in dragon's age, I even went to the trouble to save before every interaction in Tenpenny Tower and convince the members to live along side the ghouls. Man it irked me to no end when there was no radio version of the good side but I was instead defaulted to having killed the ghouls.
During my 'Modern Fallout Phase' which at the time was rediscovering fallout 3 and playing it through countless characters trying different play styles and different personalities I found myself getting bored of the starting. So every so often when restarting the game I'd slaughter megaton making sure I got everyone. This in and of itself wasn't so bad but when I started getting bored of seeing if I could survive the onslaught with a low level character I started corpse piling. This all eventually led to the discovery that when a body has been disintegrated by and explosion or dismembered its body is still connected so no matter where the parts are they count as one body. This is helpful for looting but there is another side effect of system, that being that if you set a detached arm on fire its torso will light up as well.
SO Long story concluded the most evil or more accurately horrific thing I've done is splatter/ dismember every citizen of Megaton float their heads in the centre of town around the atomic bomb, wait until night, then set them all on fire and watch the city twinkle to life as a bunch of little fires start everywhere.
Funnily enough this isn't my usual play style and I was always reload the game to a point before(seriously who doesn't want Megaton over Tenpenny)usually I have difficulty playing the 'evil' character. Did't steal in Skyrim full paragon in Mass Effect and a generally nice dude in dragon's age, I even went to the trouble to save before every interaction in Tenpenny Tower and convince the members to live along side the ghouls. Man it irked me to no end when there was no radio version of the good side but I was instead defaulted to having killed the ghouls.