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