"As the title says, what is your favourite plot twist in a video game? Anything shocking and surprising, that made you say, "holy shit, I did not see that coming" counts. Spoilers follow, obviously.
My personal favourite is from Star Wars: Knights of the Old Republic. If you've played the game, you already know what I'm talking about. I mean, this twist is greater than "I am your father" and solidified this game as one of my Top 10 favourites of all time."
Dude I came here to say the exact same thing, that game is way beyond epic