During the Season 2 Developer Update livestream, Blizzard announced that Diablo 4 is coming to Steam with the start of Season 2, October 17! After Overwatch has been added to Steam earlier this year, Diablo 4 will be Blizzard's second game to be available through Valve's game library.
While not a whole lot of details have been unveiled, Blizzard has stated that playing through Steam will still allow players to cross-play with other platforms and cross-progress their character across all currently supported platforms.
This also means that Diablo 4 will be officially playable on the Steam Deck soon! As of right now, players have to go through a lengthy installation process to be able to play Diablo 4 on Valve's handheld device. If you own a Steam Deck right now and can't wait for the official release, you can find step-by-step instructions down below on how to install Diablo 4 on Steam Deck: