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