“The Microsoft Store will also begin accepting Win32 games, not just the more restrictive Universal Windows Apps.”

Source.

Microsoft announced that it’s planning to bring more Xbox games to Steam.
Microsoft also plans to bring the Xbox Game Pass subscription service to PC, which was also announced. But it will no longer be the only way to play those first-party games on PC.

Age of Empires 1-3 ( Definitive Editions) and Gears 5 will the first games coming on Steam.

To launch these games on Steam or other stores, they will need to be repackaged as Win32 executables than UWP apps like they are on the Microsoft Store. Win32 is the main takeaway is it’s the format that all your other Windows games and programs use. If they are Win32 applications they’ll be able to support things like modding and the Steam overlay.

This now opens Microsoft to support Win32 games.