Choosing to support a faction in this way unlocks its Act Three questline and ending. While each ending has its own Act Three mission chain, a major decision point occurs during The Molecular Level at the end of Act Two: If you have the Brotherhood of Steel, Railroad or Minutemen help you build the teleporter, they'll give you an optional objective of obtaining data about the Institute. The end game state depends on decisions made during Act Two and Three. Are you ready? How do I choose an ending? We'll be explaining these choices and their consequences in detail in the rest of this article, so this is your last chance to avoid some spoilers. The ending you'll see when you finally wrap up Fallout 4's main questline depends on your choices in the second and third acts. Here's how to see the best ending in the game, whether in VR or not. With Fallout 4 having just been re-released in VR, we decided that it was time to revisit our Fallout 4 guides. Which will you choose - and what determines that choice?