Here is the full list of all 38 Ziggurat achievements.
Win a game with every character (any difficulty)
Unlock all enemies in the bestiary
Kill all enemies at least once (including bosses)
Die 50 times
Died after killing the boss
Find a super secret cheat code
Unlock all character classes
Unlock all weapons,perks,lore & character classes
Unlock all perks
Unlock all amulets
Unlock all magic weapons
Win a game on hard difficulty
Die 25 times
Win the game with Argo on Normal difficulty in less than 45 minutes
Reach floor 2 without getting damaged
Win the game without using any level up
Kill 5000 enemies
Get to floor 3 using only the magic wand (Apprentice class only)
Find all lore scrolls
Break 2,000 things (Barrels, tombs...)
Find a secret room
Die 10 times
Survive the Ziggurat
Kill 500 enemies affected with elemental states
Master a perk by getting it to level 5
You met your match in the final showdown
Kill a Lost soul with the Skull of Xanatos
Reach experience level 15
Kill 1000 enemies
Reach experience level 10
You reached 3rd floor. Now the real lesson begins.
You've been ambushed in a treasure room
You died on a danger room
Equip a weapon of every kind
Find your first amulet
Complete a challenge room
Reach experience level 5
Get your first level up