It all starts with Final Fantasy VII.
Final Fantasy 12

In 2020, Square Enix will bring pretty much every Final Fantasy game, from Final Fantasy VII onward, to the Xbox Game Pass. This means that those with active Game Pass subscriptions on Xbox One, Xbox One X, and Windows 10 will get access to these games starting in 2020.

These will be rolled out at a fairly steady rate throughout the year.
  • FINAL FANTASY VII
  • FINAL FANTASY VIII Remastered
  • FINAL FANTASY IX
  • FINAL FANTASY X/X-2 HD Remaster
  • FINAL FANTASY XII THE ZODIAC AGE™
  • FINAL FANTASY XIII
  • FINAL FANTASY XIII-2
  • LIGHTNING RETURNS™: FINAL FANTASY XIII
  • FINAL FANTASY XV
Solid release dates for these titles was not provided by Square Enix. You may also notice that Final Fantasy XIV isn't on that list. The good news is that Phil Spencer says that it will arrive on the Xbox One at a later date.

"I wanted you to know, rest assured that we will be bringing that game to Xbox. We have a great relationship with Yoshida-san and we’re working through what it means to bring [to Xbox] a cross-platform MMO that they’ve run for years."