Last week, Phil Spencer from Microsoft assured us that Age of Empires: Definitive Edition and several other titles will be released on Steam. In response to a user's question about the need to buy the game again, the official twitter account of the series ensured that there would be no need for it, as the production will support the cross-play between Steam and Microsoft Store. This means that owners of Age of Empires: Definitive Edition will be able to play freely with each other between platforms. The person responsible for the Twitter account also points out that a game purchase in one store will not unlock the title in another. However, it reminds us of the option of adding games from outside Steam, which is available in Valve's client.
Age of Empires: Definitive Edition was released on February 20, 2018 in the Microsoft store, where it currently costs $19.99. The release date of the Steam edition hasn't been announced yet.
Age of Empires II: Definitive Edition, which will also be available on Steam and Microsoft Store, will be playable during the upcoming E3 fair. According to the official website of the series, the participants will be able to experience stunning graphics in 4K and a new, fully remastered soundtrack. The demo available at the fair will allow you to get acquainted with four new civilizations.