PC players who purchase the Windows 10 version of Call of Duty: Infinite Warfare won't be able to play with those on Steam.

In a post on Activision's official support site, the publisher confirmed that the Windows 10 versions of both Call of Duty: Infinite Warfare and Modern Warfare Remastered are tied to Microsoft's ecosystem, saying, "you can only play these titles with other users of Windows 10 on Windows Store."

Source: IGN