Here is the full list of all 20 Hashtag Dungeon achievements.
Die for the first time...
Defeated the Mana Lord...
Defeat Lord Laughter...
Defeat Grandmagus Groomp...
Defeat the Plague Lord...
Collect 99999 Loot Whilst Playing
Destroy the Infernal Organ...
His programming is too strong...
Build your first dungeon room...
Upvoted or downvoted a room...
Unlock all the characters...
Killed 50 Zombies Whilst Playing
Use a summoning circle...
Magic can have otherworldly risks...
Recruit the Paladin!
Leader of the Pack!
Recruit the Ninja!
Recruit the Ranger!
Recruit the Blood Mage!
Recruit the Robot!