Here is the full list of all 45 The Fall of the Dungeon Guardians achievements.
Reach the End of the Game
Reach Level 20
Complete the Treasure Hunt
Do 1 million total damage
Reach Level 19
Double check any loose end that may save your life
"Now, look at these boots, and tell me they're not Legendary !"
Reach Level 18
Reach Level 17
Reach Level 16
Spent 15 talent points in the same Specialization Tree
Kill a boss or an elite with only 1 party member left alive with less than 5% of their HP left
Reach Level 15
Spent 7 talent points in 2 Specialization Trees
Reach Level 14
Reach Level 13
Reach Level 12
Reach Level 11
Kill 1000 enemies
Reach Level 10
Reach Level 9
Reach Level 8
Reach Level 7
Do 150 damage in one hit
Walk 10'000 tiles
Reach Level 6
Do 100 damage in one hit
Do 100'000 total damage
Pass through a fake wall
Reach Level 5
Never flee for a whole level (after level 1)
Go all the way in & out of the Fireball room without being touched by any fireball
Reach Level 4
Reach Level 3
Kill an Elite without using Active Pause
Do 50 damage in one hit
Run away from an enemy during a fight
Kill 100 enemies
Do 10'000 total damage
Walk 1000 tiles
Reach Level 2
Kill a Boss without using Active Pause
Kill 10 enemies
Walk 100 tiles
Kill your 1st enemy