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