If you're planning on purchasing Call of Duty: Infinite Warfare for your PC in the Windows store, let me stop you before it's too late. RPS reported earlier today that the game does NOT include crossplay with those who own the game on Steam, nor Xbox One. This essentially means you have zero reason to purchase the game on that platform, as a bulk of PC players will be on the Steam client. 

When asked for comment Microsoft responded...

“We support cross-play between devices and platforms for partners who want to enable it.”

In case you were wondering, this is a rare occurrence. One has to wonder why Activision would not allow for cross play between platforms on the same system! To be honest I don't know too many PC gamers who don't utilize Steam or another client, but feel like I need to get the info out there just in case!