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