Darth Vader Originally Had a Different Role in ROGUE ONE
Arguably the best part of Rogue One: A Star Wars Story is the scene where Darth Vader is murdering the rebels as they try to escape with the Death Star plans. That scene is amazing! It turns out that we almost didn’t get that scene. Gary Whitta, the screenwriter for Rogue One originally pitched the idea of Vader being on Scarif.
While it still would’ve had Vader slaughtering Rebels, I agree that the horror vibe was a lot better. I’m glad this was changed for the final release.
Source: Cinema Blend