One of Forspoken's original writers has said that the final version of the game is completely different from what he originally pitched.
Gary Whitta, possibly now best known for co-writing Star Wars: Rogue One, also served as a writer on Forspoken, though in the game he's just credited as being behind the original concept. The writer recently spoke with Alanah Pearce as part of her Video Game Writing 101 series, where he touched on Forspoken's story, which he says was rebooted between what he pitched and what the game ended up being (thanks, GamesRadar).
Pearce noted that from what she understands, Whitta had never written a single line of dialogue, which the latter confirmed, though he hasn't actually played the game so wasn't entirely sure. "What happened was, Square [Enix] came to me like five, six years ago and said 'we have this idea… would you be willing to help us build out the world and the mythology,'" Whitta explained. Square Enix apparently liked what he came up with, and subsequently asked him if he would run a writers room, which he did and got together a bunch of writers he admired.
"Some months after that, they came back to me and one of the other writers and said 'we're going to start over and completely reboot the story, we want it to be this now.' What they pitched us was something that's closer to what they actually have now, which is about this girl from the real world that gets sucked into this fantasy world."
Whitta went on to explain that the version that they had was nothing like what Square Enix came back with. But neither himself or the other writer were actually available to continue writing on the project. Whitta didn't divulge in any specific details as to what he actually contributed, again, he isn't entirely sure other than the name of the setting, Athea, as he did come up with that, so it's possible some of the foundational lore he developed was used in the final game.
VG247's Forspoken review didn't paint an entirely favourable picture of the game, giving it a 3/5, saying, "Its stuttering start belies a combat system that’s worth investing the effort to learn, but takes so long to get up to full speed that it’s already on borrowed time."