Full list of all 101 Skul: The Hero Slayer achievements.
The base game contains 57 achievements, and there are 5 DLC packs containing 44 achievements.
Restore the Demon King Castle to its original form
Defeat the First Hero without getting hit
Defeat the First Hero without saving the stage NPC
Defeat St. Joan II without getting hit
Play on Rookie Mode
Acquire Gold Gargoyle
Acquire Super Rock Star
Acquire Joker
Acquire Dark Avenger
Acquire Magnifico
Acquire Destroyer
Acquire Master Ninja
Acquire Nightmare
Acquire Sniper
Acquire Eternal Mummy
Acquire Demolitions Expert
Acquire Dark Alchemist
Acquire Vanguard Captain
Acquire Warlord
Acquire Devil Berserker
Acquire Elder Ent Skull
Acquire Poseidon
Reach the top of the chandelier in the Demon King Castle
Acquire Abyssal Monarch
Defeat Chimaera without getting hit
Defeat the Leiana Sisters without getting hit
Defeat the First Hero as Little Bone
Acquire Defender Captain
Kill 100 adventurers
Acquire Minotaurus III
Acquire Desperado
Acquire Carleon Commander
Rescue the Demon King and return to the Demon King Castle
Defeat the Sword of Carleon, the First Hero
Acquire Soul Knight
Acquire Neo Samurai
Acquire Gambler
Acquire Eternal Werewolf
Acquire Frozen Spirit
Defeat the archbishop of the Leonia Order, St. Joan II
Acquire Grim Reaper
Acquire Royal Guard Captain
Acquire Arch Lich
Defeat Yggdrasil without getting hit
Defeat the distorted goddess, Chimaera
Acquire Ghoooooul
Acquire Yaksha
Acquire Champion
Keep talking to Headless
Keep restocking from the collector
Stay in the black market for 5 minutes
Defeat the adjutants of the Gold Mane Knights, the Leiana Sisters
Defeat the elder ent, Yggdrasil
Return after experiencing death
Die from a trap
Stay in the black market for 1 minute
Reach the top of the throne in the Demon King Castle