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
Spent 7 talent points in 2 Specialization Trees
Reach Level 19
"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
Reach Level 15
Double check any loose end that may save your life
Reach Level 14
Reach Level 13
Do 150 damage in one hit
Reach Level 12
Kill 1000 enemies
Reach Level 11
Reach Level 10
Walk 10'000 tiles
Reach Level 9
Reach Level 8
Do 100 damage in one hit
Reach Level 7
Reach Level 6
Do 100'000 total damage
Pass through a fake wall
Reach Level 5
Reach Level 4
Never flee for a whole level (after level 1)
Reach Level 3
Kill an Elite without using Active Pause
Do 50 damage in one hit
Walk 1000 tiles
Reach Level 2
Kill 100 enemies
Do 10'000 total damage
Kill a Boss without using Active Pause
Run away from an enemy during a fight
Kill 10 enemies
Kill your 1st enemy
Walk 100 tiles
Kill a boss or an elite with only 1 party member left alive with less than 5% of their HP left
Do 1 million total damage
Go all the way in & out of the Fireball room without being touched by any fireball