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