Stranger Things Day celebrations for 2026 hit with a bang, with Netflix announcing a new spin-off series. Other Worlds: A Stranger Things Adventure is a prequel series set in the 1950s, created by the Duffer Brothers and longtime Stranger Things writer Kate Trefry. It is set before the events of the award-winning stage play Stranger Things: The First Shadow in 1959, which explores Henry Creel's past.