Kinda funny that they waited before announcing this.

"Don’t miss the Gameplay Preview Video for Overwatch Rush, an upcoming mobile top-down hero shooter developed by Blizzard. Players will duke it out in a new experience within the Overwatch Universe to take the fast-paced 4v4 action on the go with characters, abilities, and weapons from the core Overwatch game.

Get an early look at a development build for Overwatch Rush, coming soon to iOS and Android."