Here is the full list of all 31 Princess.Loot.Pixel.Again x2 achievements.
Find glory
Complete Warrior missions
Find the grail
Save Princess
Complete Paladin missions
Kill a dragon
Beat Dark Thief mission
Beat Dark Warrior mission
Kill rats
Kill traitor
Complete Thief missions
Theft golden dagger
Theft crown
Beat Dark Paladin mission
Blink!
HA HA HA!
You are serious??
Save a cat
Beat the boss
Collect 99 coins
Find Mush and Flower
Kill boss without damage
Find the Guitar
Find Fez hat, Meat cube and Scarf
Complete level without damage
Find Crying baby
Steal coins
Dead first time
Find secret place