Here is the full list of all 14 24 Killers achievements.
Collect your first Whisper.
Drink a Shabstar on a Blood Moon.
Get your Whisper Multiplier to 10x.
Heal all desert areas.
Complete Moon's scrap book.
Meet the Husbandman.
Acquire the cursed Whisper.
Unlock all save files.
Acquire all blessings.
Produce a poo.
Acquire 1000 Whispers with one capture.
Beat the game in 24 days or less.
Free all the mons.
Complete the birthday card.