From polygon:
Maybe don’t buy Call of Duty: Infinite Warfare from the Windows 10 Store
Windows Store copies don’t play nice with other platforms
Call of Duty players who purchase a PC copy of Call of Duty: Infinite Warfare and Call of Duty: Modern Warfare Remastered from the Windows Store on Windows 10 won’t be able to play with people on other platforms, like Steam, according to an update on Activision’s support website.
Infinite Warfare and Modern Warfare Remastered won’t support cross-platform play between Windows PC and Xbox One — the titles aren’t part of Microsoft’s Xbox Play Anywhere program. That’s not much of a surprise; the majority of Xbox Play Anywhere supported titles are developed or published by Microsoft.
More surprising, however, is the lack of cross-platform compatibility on PC. Buying the games for Windows 10 from the Windows Store will apparently restrict players from playing with PC gamers who purchase it elsewhere. From Activision’s support website, via NeoGAF:Can I play Call of Duty: Infinite Warfare or Call of Duty: Modern Warfare Remastered for Windows 10 on Windows Store with my friends that are playing on another PC platform?
No, you can only play these titles with other users of Windows 10 on Windows Store.
Q: Why would anyone buy games from the Windows 10 Store? They always seem to have some weird issue that the Steam/Windows 7 version just doesn't have, and they're never better.
I stand by my theory of yesterday: Steam users may have mostly switched to Windows 10, but it's not out of any great love of Windows 10. They all just figured they'd be forced to switch anyway, so they got it over with. They're not loving the new OS, they're not loving Universal Windows Apps, they're not loving the Windows 10 Store's offerings, and shit like this is not helping to change any of that.