Here is the full list of all 22 Hellmut: The Badass from Hell achievements.
Kill one of every enemy type.
Collect 5,000 Soulstones cumulative.
Stay in the shop for more than 20 minutes continuously.
Use every weapon.
Kill The Demon at least 10 times after receiving Professor Transformation.
Unlock all Transformations.
Acquire Professor Transformation.
Enter dungeons as the Orc Fairy.
Play with all Transformations except the Professor.
Do 15.000 damage with barrels.
Buy one of each item type in shop.
Complete one playthrough in under 20 minutes.
Shoot 1,000 enemies with a single weapon.
Don't lose a single hitpoint in one level.
Kill at least three enemies with an exploding barrel.
Defeat The Demon.
Deal over 100,000 cumulative damage.
Shoot 10,000 shots.
Complete Challenge mode in under 1 minute.
Die for the first time.
Enter dungeons as the Rat King.
Complete Tutorial.