1
2
3
4
5
There could be some sort of memory/date leak that is corrupting Windgate Creek. Maybe it has created monsters where normally this City wouldn’t have them. The leak could also cause people’s memories to become jumbled if they spend too long there (leading to them kind of becoming NPCs). But the ‘fix’ would be center around fixing the leak. Though the closer characters get to the leak location, the more jumbled their memories become.

or

Players go to Windgate and its inhabited by monsters. The monsters are actually the NPCs of the place and they need to be ‘fixed’ because the Archway can be habitable.