Here is the full list of all 41 Kill The Cute achievements.
Die 3 times
Die 20 times
Die 50 times
Kill 200 Cutelings
Kill 2.000 Cutelings
Kill 20.000 Cutelings
Complete a run on 1st Difficulty
Complete a run on 2nd Difficulty
Complete a run on 3rd Difficulty
Complete a run on 4th Difficulty
Upgrade weapons 10 times
Bosses fled 20 times
Defeat bosses 30 times
Reroll 100 times
Complete a round with 1 HP left
Complete a round with 1 HP left when you play as Vampire
Complete a run with Demon
Complete a run with Ice Mage
Complete a run with Sharp Shooter
Complete a run with Veteran
Complete a run with Berserker
Complete a run with Viking
Complete a run with Necromancer
Complete a run with Agent
Complete a run with Ninja
Complete a run with Viper
Complete a run with Soul Eater
Complete a run with Specialist
Complete a run with Golem
Complete a run with Lunatic
Complete a run with Vampire
Complete a run with Demon Hunter
Complete a run with Electro
Complete a run with Yakuza
Complete a run with Boomer
Complete a run with Rotten
Complete a run with 21st Character
Complete a run with 22nd Character
Complete a run with 23rd Character
Complete a run with 24th Character
Unlock 25 Skill Tree perks