Here is the full list of all 24 FINAL FANTASY achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Earned all achievements.
Defeated Chaos and restored peace to the world.
Completed 100% of the Bestiary entries.
Collected treasure from 100% of the chests.
Obtained Excalibur.
Restored the Wind Crystal's light.
Traveled to all the map locations.
Restored the Water Crystal's light.
Restored the Fire Crystal's light.
Completed 50% of the Bestiary entries.
Collected treasure from 50% of the chests.
Defeated 500 monsters.
Reached level 50 for all party members.
Defeated 300 monsters.
Gained titles of courage from Bahamut.
Restored the Earth Crystal's light.
Defeated 100 monsters.
Collected treasure from 10% of the chests.
Played the 15 Puzzle game.
Completed 10% of the Bestiary entries.
Obtained 100,000 gil.
Saved Princess Sarah by defeating Garland.
Obtained 50,000 gil.
Obtained 10,000 gil.