Here is the full list of all 20 Dead Dungeon achievements.
View credits
Defeat the boss
Collect all collectables
Collect all donuts
Die 1000 times
Complete 40 levels
Die 500 times
Find the second secret level
Kill the enemy in an unexpected way
Complete 30 levels
Find the first secret level
Activate the trap
Complete 20 levels
Die 100 times
Kill 100 enemies
Use the portal
Complete 10 levels
Find first collectable
Kill the first enemy
Die for the first time