Scott Cawthon, the creator of the Five Nights at Freddy’s series, is teasing a mysterious collaboration in the works, with an announcement expected later today.

Since Aug. 1, Cawthon has been dropping announcements and teases about the FNAF franchise as part of the franchise’s 10th-anniversary celebrations. These drops have included a behind-the-scenes look at the second FNAF movie and the announcement of a fan-game demo on Steam—but it’s today’s announcement of a mystery collab that has fans stumped.