Blizzard is teasing a new Overwatch event on Twitter. The company posted a brief video stating an archive declassification will unlock mission files on April 10, 2018.
The video clip released alongside the tease references a specific point in Overwatch lore. Null Sector, a terrorist group, started an uprising and set London on fire. Overwatch was forbidden from intervening, except McCree was already on the ground as part of a Blackwatch mission and Mercy, Reinhardt, Torbjorn and Tracer were sent in by Soldier: 76. What happened while the agents were there is classified.
Overwatch is available for the PlayStation 4, Xbox One and PC.