Here is the full list of all 15 DRAGON: A Game About a Dragon achievements.
Defeat the Admiral without taking damage.
Trick a Lancer into dashing down a pit.
Get Dragon to whistle three particular songs.
Have 10,000 gold at once without depositing it at home.
Defeat TM-061 without taking damage.
Defeat Boudouin and Alex without taking damage.
Defeat the Bishounent without taking damage.
Defeat the king's bodyguards without taking damage.
Learn to use Magic Breath.
Find five very special treasures.
Find the Stannum Sollerets and all five gemstones.
Complete the NPC's secret sidequest.
Clear the game without increasing your HP from taking damage.
Finish the game with the regular ending.
Finish the game with the best ending.