Here is the full list of all 40 The Vagrant achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Achieve normal ending
Clear the game in Hard difficulty
Unlock all achievements
Collect 1000000 mana
Acquire all skills
Unlock all abilities
Collect 1000000 gold
Failed to defeat Shroom prime
Failed to stop Soulreaper
Failed to defeat Kumasith
Achieve 999 combos
Achieve 500 combos
Defeat Soulreaper
Achieve true ending
Unlock all entries in Note
Unlock all entries in Monsterpedia
Defeat Valerie
Explore all areas
Acquire Sword of verum
Acquire all recipes
Slay the chicken
Defeat Fallen Kumasith
Defeat Shroom prime
Defeat Ground shaker
Stop Soulreaper
Slay 666 monsters
Defeat Santiago
Failed to defeat Santiago
Consumed 100 potions in total
Defeat Headless horseman
Keep drinking potions
Defeat Kumasith
Defeat Maximillian II
Defeat HMWV
Acquire a max ranked weapon or armour
Acquire a weapon or armour with 4 runestones
Defeat Esgonian general
Fight Soulreaper
Achieve 100 combos
Acquire an onion from the chef in Brocley village