Here is the full list of all 22 99 Levels To Hell achievements.
Beat the Devil
Beat the 8th boss
5 hours in the dungeons
Found the Dragon
Beat the 6th boss
Beat the 7th boss
Beat the 9th boss
Beat the 3th boss
Beat the 4th boss
Beat the 5th boss
Spill 1000 liters of blood
2 hours in the dungeons
Beat the 2nd boss
Beat the 1st boss
Found the Major
Used a cheat code
Ghost?
Found the Hunter
Found all the hidden books
Collect 10.000 gold
Die 100 times
10 hours in the dungeons