Here is the full list of all 37 FINAL FANTASY VI achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Earned all achievements.
Defeated Kefka and restored peace to the world.
Obtained all magicite.
Traveled to all the map locations.
Collected treasure from 100% of the chests.
Obtained all hidden items.
Completed 100% of the Bestiary entries.
Reached level 50 for all party members.
Defeated 2,000 monsters.
Obtained 500,000 gil.
Acquired all "Bushido" commands.
Got "Joker's Death" with the "Slot" command.
Used the "Leap" command to learn 50 enemy techniques.
Obtained all "Tools" commands.
Acquired all "Blitz" commands.
Learned 20 enemy techniques.
Won 10 battles in the coliseum.
Reunited with 10 allies.
Completed 50% of the Bestiary entries.
Reunited with 5 allies.
Defeated 1,000 monsters.
Reunited with 1 ally.
Witnessed the Warring Triad revive and destroy the world.
Collected treasure from 50% of the chests.
Attended Emperor Gestahl's banquet and brokered peace.
Obtained 100,000 gil.
Obtained 15 pieces of magicite.
Won an item at auction.
Performed in the opera and obtained the airship.
Encountered Ramuh and obtained his magicite.
Protected the frozen esper and ousted the Imperial troops.
Completed 10% of the Bestiary entries.
Defeated 100 monsters.
Met with Banon and decided to oppose the Empire.
Collected treasure from 10% of the chests.
Obtained 10,000 gil.
Encountered the frozen esper and awakened elsewhere.