Chutes and Ladders
Time is slippery.
Examples of people who seem 'out of time' have been passed down in stories and pointed out in photos. Some seem to have slipped into the wrong time accidentally, while others seem to be hiding there.
Discovering himself in the middle of a creepypasta mystery, the protagonist will connect the dots and find himself entangled in his own history and the people who he thought he knew his whole life.