Here is the full list of all 49 WORLD OF FINAL FANTASY achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Completed every last intervention battle.
Brought all seven of the Pleiad back in line.
Defeated Ultros in Tometown.
Joined forces with Shivalry to defeat the Golden Flan.
Chastised the fugitive Ifreeta.
Completed 30 intervention battles.
Reached an ending.
Learned the location of Castle Exnine.
Obtained every last Champion Medal.
Teamed up with Gilgamesh to stop the Bahamutian soldier.
Recorded a huge number of Mirages in the Mirage Manual.
Battled 500 times.
Found all of the keys from the Crimson Prophecy.
Opened 100 treasure chests.
Completed 10 intervention battles.
Obtained your first Champion Medal.
Found the first key from the Crimson Prophecy.
Got to the bottom of the “phenomenon” at the Coliseum.
Recorded a large number of Mirages in the Mirage Manual.
Defeated your first murkrift Mirage.
Battled 100 times.
Completed your first intervention battle.
Won your first Coliseum battle.
Repelled the Bahamutian Army.
Fulfilled a townsperson’s request for the first time.
Imprismed your first Mirage.
Arrived in Grymoire.
Obtained every achievement.
Reached the true ending.
Recorded an inconceivable number of Mirages in the Mirage Manual.
Recorded every last Mirage in the Mirage Manual.
Mastered your first Mirage Board.
Mastered 100 Mirage Boards.
Opened every last treasure chest.
Defeated every last murkrift Mirage.
Found the secret area in every dungeon.
Fulfilled the requests of every last townsperson in need.
Added Tamamohimé to your roster.
Defeated the Quacho Queen with one of Lann’s attacks.
Defeated the Undead Princess 10 times.
Defeated the Princess Goblin with the Warrior of Light.
Defeated 30 teams at the Coliseum.
Defeated every last opponent in the Coliseum.
Braved and completed the new dungeons that appeared.
Defeated the Cogna known as XG.
Defeated many foes using any Magitek armor.
Cleared the sky of uncountable einhänders.
Reached the final chamber of the Nether Nebula in record time.
Thwacked a whole bunch of cactuars in a single thrashing.