The reason I love Fallout so much is not because of the graphics because they are ok, but it's the gameplay mechanics & the limits this game lets you achieve that most games dare not, like killing a main story character, but the game goes on and you just won't be able to do that mission or you can just find another way to complete it.
It's almost like you make your own story as you go, in fact it took me a year just to beat the main game because I was too busy messing around it huge open world filled with interesting characters & locations.
I also love the Karma System, hopefully the mastered it in the new Fallout 4.
The combat is cool too! Being able to shoot and cripple an enemy or shooting a limb off like the head is awesome, but I know it's gory for most, but hey! I love it lol Oh did I mention this game is FUN! I wouldn't mind Multiplayer!