Here is the full list of all 43 Chronos: Before the Ashes achievements.
Complete the Game at age 21 or younger
Complete the Game on any Difficulty
Defeat the Dreamer
Defeat the Labyrinth Guardian
Unlock Your First Trait
Upgrade Any Weapon to Level +5
Acquire the Labyrinth Scythe
Return a Keepsake to the Krell King
Exchange your Starting Weapon with a Krell Version
Acquire the Shadow Stone
Defeat the Pan Guardian
Acquire the Pan Shield
Read 10 Books or Scrolls
Defeat the Red Widow
Solve the Flautist Riddles
Meet the Pan Flautist
Create a Rare Dragon Shard
Put 30 Attribute Points into Strength
Put 30 Attribute Points into Vitality
Acquire the Pan Spear
Acquire the Lightning Stone
Craft a Krell Mace
Defeat the Stone Golem
Acquire the Krell Hidden Weapon
Acquire the Krell Shield
Defeat the Krell Guardian
Read 5 Books or Scrolls
Acquire the Krell Hammer
Upgrade Any Weapon
Acquire the Fire Stone
Meet the Krell Blacksmith
Open a Dragon Inscribed Box
Acquire a Dragon Heart
Travel to Ward 16 by Way of the Mirror
Acquire the Sun Stone
Put 30 Attribute Points into Agility
Put 30 Attribute Points into Arcane
Complete the Game on HEROIC
Complete the Game on ADVENTURE
Unlock Everything
Upgrade Any Weapon to Level 9
Complete the Game in NG+ Mode