Here is the full list of all 15 bit Dungeon II achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Slayed the Fiend.
Free the ghost from her grave.
Slay the Demiurge.
Tis this a demon?
Enter into the Dark World.
Find an epic-quality weapon.
Kill the leader of the Thief Kings, The Cursed Wizard!
Kill the king of Skeletons.
You have died. You have all lost things. You can not take your possessions with you to the next incarnation.
Destroy the Soul Collector.
She rules an army of beasts in the Black Church, defeat The Yaldabaoth.
Face The Eater!
Reach level ten.
Slay the Fire Nob Glob.
Kill a mini-boss.