Here is the full list of all 24 Princess.Loot.Pixel.Again achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Necromancer saves King
Make four deals with the cat in one run
Collect 3000G in one run
Collect 46 artifacts
Berserk saves King
Collect 15 artifacts in one run
Press TAB in the main menu
Warrior saves King
Candlevania!
Archer saves King
Get Rank C
Collect 23 artifacts
Make a party!
Find hidden place
Explode the door
Get Rank S
Get Rank A
Find baby
Get Rank B
Die for the first time
Start main Quest
Mage saves King
Rogue saves King
Paladin saves King