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