Square Enix brought back Final Fantasy Adventure (Game Boy) for modern mobile devices. It's now called Adventures of Mana and can be yours for $13.99 (USD) for either iOS or Android.
ADVENTURES OF MANA, originally released as FINAL FANTASY® Adventure for the Nintendo Game Boy in 1991, tells the epic story of a group of trusted companions on a journey to protect the sacred life-giving Mana Tree from the powerful Dark Lord of Glaive. ADVENTURES OF MANA offers fans the magic of the action RPG enhanced with stunning 3D visuals, revamped menus and a rearranged soundtrack from the game’s original composer, Kenji Ito.