Following E3, Microsoft announced that every first-party game on Xbox One would feature Xbox Play Anywhere compatibility with PCs. Meaning, buying Gears of War 4 on Xbox One gets you the PC version for free, or vice versa. You'll also be able to carry over game progress and achievements.
YouTube personality 'The Red Dragon' (via IGN) points out that Play Anywhere may not apply to all first-party titles due to a slight alteration in the wording of Microsoft's outline of the initiative.
"With the Xbox Play Anywhere program, you can buy a game once and play on your Windows 10 PC and Xbox One with shared progress, shared game saves and shared achievements," wrote Yusuf Mehdi, Microsoft's corporate VP of the Windows and Devices Group.
Here's where Microsoft tweaked its original wording. "Every new title published from Microsoft Studios that we showed onstage at E3 this year will support Xbox Play Anywhere and will be easily accessible in the Windows Store," the announcement now reads. But according to The Red Dragon, the statement originally read "every new title published from Microsoft Studios will support Xbox Play Anywhere."
The full list of Xbox Play Anywhere titles includes Gears of War 4, Forza Horizon 3, Sea of Thieves, State of Decay 2, and others mentioned here.
While it's still possible that all future first-party games published for Xbox One will be compatible with Windows, Microsoft's adjustment implies that it might be hedging its bets depending on the success of the Xbox One S and next year's Scorpio revision to the console's hardware.