Something is coming to Overwatch, and it’s a secret until later this month.

Blizzard Entertainment has uploaded a video that teases something mysterious for the world of Overwatch, the developer’s sci-fi hero shooter for PC, PlayStation 4, and Xbox One. The clip mentions something about the King’s Row Uprising, and Blizzard’s posts on Facebook and Twitter say it is “initiating archive declassification” and the files will unlock on April 11 (even though an earlier, now-deleted version of the video said April 12). The video also claims the “confidential” files are seven years old and somehow relate to mandatory robot registration.

This could mark the beginning of another alternate-reality game (ARG) now that Blizzard has had several months off from the ARG that introduced the hacking attack character Sombra. It could also involve one of Blizzard’s Overwatch comic books or short films.

Here’s a look at the video Blizzard uploaded to Twitter:

The most telling part of this teaser is the info about the “King’s Row Uprising.” King’s Row is a map in Overwatch as well as a sanctuary for the Omnic race of sentient robots. It’s possible that the classified files may fill in some backstory of how that protected enclave came to pass.

It seems unlikely that this would have anything to do with a new character considering Blizzard only just introduced the tank Orisa into the roster. The developer will likely want to take several months to ensure it can properly fit that hero into regular play. But whatever the Kings Row Uprising data is, I’ll keep an eye on it and any other developments in Blizzard’s megapopular shooter.