The final mobile announcement from the Square Enix E3 showcase was War of the Visions: Final Fantasy Brave Exvius focussed. Square Enix announced the game a little while ago for a 2019 release in Japan. It is a tactical RPG spinoff in the Final Fantasy Brave Exvius (Free) universe from Square Enix. Watch the original announcement trailer below:

I speculated about the platforms given the developer (Gumi Inc.) and the series involvement and that has been confirmed. War of the Visions: Final Fantasy Brave Exvius releases on iOS and Android this year and will see a global release. I love the visual style and will definitely give it a shot when it releases on iOS. Watch the global announcement trailer for it below:
War of the Visions: Final Fantasy Brave Exvius will release on iOS and Android devices globally this year. Check out the official English website for it here. Given that Square Enix loves doing cross game collaborations, get ready for many of their games to have some events with Final Fantasy Brave Exvius soon. What do you think of Final Fantasy Brave Exvius"

...