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