PC Call of Duty: Infinite Warfare may be temporarily cheaper on the Windows 10 Store (£33) than on Steam (£40), but if you buy from the Windows Store, you will not be able to play with people who buy on Steam.
The Activision FAQ asks: "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?"
The Activision FAQ answers: "No, you can only play these titles with other users of Windows 10 on Windows Store."
Modern Warfare Remastered, remember, is locked away for owners of the more expensive Digital Legacy edition of COD: Infinite Warfare, which is also temporarily cheaper on the Windows Store - £48.50 to Steam's £60.
The Windows 10 Store version of COD: Infinite Warfare also does not support Xbox One cross-play, nor is it an Xbox Play Anywhere game, so you won't automatically own it on two platforms - PC and Xbox One - when buying on one.
Whose idea was it to segregate multiplayer? Activision's, it seems. In a comment supplied to Windows Central, a Microsoft spokesperson said: "We support cross-play between devices and platforms for partners who want to enable it."
In reality it will mean COD: Infinite Warfare's multiplayer community will be much smaller in the Windows 10 Store ecosystem than in Steam's. That's putting it politely; it'll probably be a ghost town. But that may not be such a bad thing, depending on how fierce you like your competition, and it will make no difference if you play no multiplayer at all.
COD: Infinite Warfare launches today. We've taken a long look at the COD: Infinite Warfare campaign already, but we're spending a bit of time with the game's launch service before providing a full review.