There's like a dozen (ETA: at least!) of great ideas in this thread! Super exited to see all these games.
I think I might want to play with the idea of a person caught in some kind of time travel/flashback scenario gone wrong. Trying to hang on to their memories and find a way to communicate with their loved ones outside of their weird lost-in-time situation. Some touchstones for me are 12 Monkeys, that one episode of Lost (The Constant, I think), parts of The Butterfly Effect, Insterstellar, Memento, The Jacket and so on.
I think the main threat in the scenario is slipping away into oblivion, becoming unable to reach other people, and losing your memories and sense of self.