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