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.
Get Rank B
Press TAB in the main menu
Die for the first time
Find hidden place
Get Rank A
Start main Quest
Warrior saves King
Archer saves King
Mage saves King
Get Rank C
Get Rank S
Rogue saves King
Paladin saves King
Make four deals with the cat in one run
Find baby
Collect 15 artifacts in one run
Make a party!
Collect 23 artifacts
Collect 46 artifacts
Candlevania!
Explode the door
Collect 3000G in one run
Berserk saves King
Necromancer saves King