Here is the full list of all 33 Young Souls achievements.
Kill Marl
Upgrade a weapon or armor
Beat Dinkoy
Dodge an attack by rolling
Block 10 attacks
Parry an attack
Kill a goblin for the first time
Kill Tetcha
Kill Fazmore
Kill Dinkoy
Kill Shinjo
Kill Kah-Kon
Rescue the Professor
Help the Professor to bury the Digger under rocks
Defeat Dwarvengobben
Ride a dragon for the first time
Beat Yarlanda in the last Mausoleum
Earn 5 stars on a Happy Fit training session
Complete a dungeon without taking any damage
Upgrade a weapon to 6 stars
Upgrade an accessory to its maximum level
Equip an armor and helmet combo
Collect 25,000 gold
Collect 50,000 gold
Collect 100,000 gold
Clear all Catacombs
Clear all hard branches
Open all bronze key chests
Open all silver key chests
Open all gold key chests
Finish the game at least in Challenging mode
Finish the game in Expert mode
Complete the game at 100%