Notice what I'm saying. I'm not saying Fallout 4 could ever be a worthy successor to New Vegas, but it can be a passable game. With the dialogue extender from Cascadia and the no level limit for perks. Hear me out, you might like what I have to say: First, let's address the biggest concern in the room: Boston needs to be changed. It needs to be rebuilt and civilized like Vegas, and everything there depends on it. Main quest changes: Make the other stasis pods in 111 locked but it's inhabitants alive. You can't get them, but it makes the Institute less petty and stupid. Make it possible to infiltrate Vault 14 or persuade them to let you in. Maybe find a guard, knock him out, take his clothes. Or if female, pose as the evening's entertainment. Make it so no part of the missions requires you to kill or run from anyone. Have the Old North Church be inhabited and have the crypt locked with the Pastor having a key. You should have to do one or two local quests before he'll trust you enough to give you the key. Or you can pickpocket him. He'd have to be essential because if you killed this man realistically the Railroad would aggro to you, but them's the breaks. Make it possible to convince Kellog to walk away. In fact, don't let him die, only once he's defeated, the player can choose the spare him, and skip the whole brain trip. Shaun needs to be rewritten. Everything about the man is manipulative and cold. Shaun needs to be friendier, a more symapthetic, with multiple scenes of interaction You don't have to aggro either the Brotherhood or the Institute on the Mass Fusion building. The building and interior need to look like a functional post-war office space, but none of the combat needs be changed. The city government won't dare say no to the Brotherhood and the Institute goes where it wants. Maybe add some Securitrons hostile to both parties. Be able to convince the Railroad to go underground in both Institute and Minuteman missions. Bluff Father into thinking you're going to blow up the Institute, then take it over and make it a base for your faction (optional) Except for rewriting Shaun, it would be rather light work, as far as mods go. The big issue would be making Boston civilized. I think the simplest way is to make a Vegas-like wall around the upper two-thirds of Boston (Downtown, the Mass. State House, the Library, the Fens, the Commons, the Docks) and rebuild those parts, leaving the bottom third as ruins. Then you can invent all kinds of side quests. I was thinking things involving skill checks, a questline to defeat or negotiate with the Gunners to leave Gunner's Plaza. They are upset about the city hiring them and not paying them, as agreed to. They are nasty, but it would be possible to do quests for them that would "convince them" to leave their various outposts, or you could kill them as per vanilla and be rewarded for it. It's not a trivial amount of work, but it's a lot less work than trying to rewrite EVERYTHING.