Here is the full list of all 25 Numgeon achievements.
Unlock all Color Palettes
Destroy 100K Numbers
Destroy 50K Numbers
Use Start-Up machine 100x
Save the Dragon
Complete 100 Missions
Destroy 10K Numbers
Finish the game on Expert difficulty
Finish the game with Knight
Use Bonfire 100x
Use Shrine 100 times
Finish the game with Sorcerer
Make 1000 Combos
Destroy 5000 Numbers
Visit the shop 100x
Die 100 times
Use Magic 100x
Destroy 1000 Numbers
Drink 100 Potions
Slay the Princess
Finish the game with Assassin
Open 100 Treasure Chests
Eat 100 Apples or Breads
Destroy 500 Numbers
Destroy Your First Number