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