That snapshot montage you saw was the "ending". The Castle won't be attacked except by Radiant quest or random wandering foes. You have sort of by default sided with the Minutemen and Railroad, looks like. Nothing but Radiant quests going forward (but that's the case regardless of which faction you END the game with).

Yeah, I just read through an outline of the quest lines from each faction choice, and it looks like I've already done all the Railroad quests. This is really lame, because Des kept asking earlier if I'd side with Railroad instead of Minutemen, so I was expecting an eventual battle between the two, yet it turns out that is the only faction they're willing to work with if need be. So why would she insist I choose between the two?

The problem is, the save I set aside is AFTER agreeing to work for the Railroad vs Minutemen, when she asked that, because people were saying your choice there doesn't really affect anything, but apparently it does.

At any rate, seems they've really botched an otherwise great game with very vague and lame ending scenarios, which I wasn't expecting at all. They didn't even run any credits, feels unfinished really.

Because it tells you bit about what kind of person she is and confirms that the Railroad will never do anything to make the Commonwealth a better place for anyone who isn't a Synth.

It doesn't affect anything. The only way for the Railroad to become the enemy of the Minutemen is to not activate the evacuation signal before blowing up the Institute, thus resulting in death of countless Synths.

Bethesda NEVER runs credits after you finish the MQ (besides maybe the FO3 without Broken Steel as you couldn't keep plying after finishing the MQ).

In any case, the Minutemen ending is definitely unfinished or underdeveloped and is kind of a Failsafe ending. It also doesn't have MQ achievements and has the poorest MQ quests, not to mention Beth kind of made it hard to even get into their route.

Well, there is still blowing u Prydwen. If you aren't an enemy of the BoS, kill one of their named characters and you will get the MM variant of blowing everyone's favorite blimp.

You see, now that right there is part of what I'm talking about. You start out the game with them giving you Minutemen introductions and quests right off the bat, with Preston appointing you "General". Then you come to find it's the most loosely written, hardest faction to receive main quests from in the end, despite all your settlement dwellers recognizing you and the Minutemen as their General and allies.

Anyway, the reason I set aside my save where I did, despite it being AFTER agreeing to work for Railroad vs Minutemen, is because at that point all factions were still peaceful with me. I think I can still finish with Minutemen from that point, if I fail Underground Undercover, but I'm not really sure, because I've read that just means Des sends you to get help from the Minutemen. I don't know if that would get me Minutemen end game options, especially Defend the Castle.

The MM end quests only occur once you turn the Institute hostile.

Well, look at it this way: no matter what ending you choose, the Minutemen win. As such, every ending is the Minutemen ending. Maybe that's why Beth was not so interested in them and why it looks like they were not originally supposed to even have their own ending.

I'm also hearing some say you can start doing end of story quests with Minutemen just by killing a BoS named character, but that doesn't appear to be the case from what I've just tried. In fact I've tried toting Preston along to kill all occupants at Cambridge Police station and the Railroad HQ, and he still is just a vague, unresponsive idiot.

I've read that the Defend the Castle quest involves waves of enemies from BoS, The Institute, and Super Mutants, so why would only getting The Institute hostile trigger a response from them? And how do you even get The Institute hostile without getting trapped inside the Institute? I already tried that and there was no way to travel out of there.

I'm sorry, I was really likjing this game, but despite the great gameplay halfway through the game, the way faction alignment plays out, and especailly the ending itself, is just horrible.

have you tried killing the named characters at the Boston Airport?

"Defend the Castle" is a radiant quest that handles ANY attack on the castle, be it a radiant attack from Supermutants or the MQ attacks from the Institute and the BoS.

MM require you to be hostile to the Institute because otherwise the MM and the Institute are treated as allies.

In case of the BoS, "Defend the Castle" is the final quest.

You can reject Shaun's offer to join the Institute, get into a heated argument with him in some dialogues (most popularly after "Battle for Bunker Hill"), killing a named character or by accepting by the Minutemen soldier's request during the quest "Pinned". If you want to take down the BoS, the Pinned route is the best because by the time you reach this quest, BoS will become hostile and the quest "Pinned" gives you a natural entry into the Minutemen route.

You can leave the Institute via the relay you came with, but first you must put into a terminal the holotape that Sturges, Ingram or Tinker Tom gave you.

I'll try killing a BoS at the airport then. What I'm trying to set up is a Defend the Castle scenario that at least tries to feel epic.

I don't think so, it's in G4's quest guide as a Minutemen end story main quest, and I just got confirmation of that after informing BoS about The Institute's plan with the reactor. After speaking with the legless BoS chick after securing the device, I went straight to Sanctuary and Preston FINALLY gave me the response I was looking for about the Castle needing help. Ronnie spoke of an impending attack from The Institute, and it showed in the main quest area as "Defend the Castle".

I've also read if you don't have enough settlements and Minutemen loyal settlers, you'll first get a preparation quest to recruit 8 settlements. Since I already had all the settlements unlocked and populated, I didn't get that, but it was a fairly epic battle, even though it was just The Institute. I've read it can involve waves of Institute, BoS, and Super Mutants, depending on what happens prior. When it's all Institute enemies though, it might actually be harder, because a lot are invisible Coursers, and there's no chance of separate invading factions warring with one another.

Furthermore this quest didn't just end by speaking to Preston like radiant quests, it's followed by another main story quest about Sturges having found a secret way into the Institute without teleportation.

So this is what I was looking forward to. I may go back and try it again after killing a BoS member too.