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