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