GuessKin is a free daily taxonomy guessing game. Pick a category — animals, languages, minerals, dog breeds, and more — and try to identify the mystery item. With each guess, the game reveals the nearest common ancestor between your answer and the target on a real classification tree. The closer the shared ancestor, the warmer you are.

Think of it as Wordle meets the tree of life. Instead of letter-by-letter clues, you get taxonomic clues: which family, which order, which branch of the tree your guess shares with the answer. Over time, you build genuine knowledge of how things are classified and related — from biological taxonomy to language families to mineral classification systems.

Every category uses a real classification system. Animals follow phylogenetic taxonomy. Plants use the APG IV system. Musical instruments use the Hornbostel-Sachs classification from 1914. Birds follow the IOC World Bird List. Minerals use Strunz classification. These are the same systems scientists and specialists actually use.

Each round starts with a mystery item hidden somewhere on the taxonomy tree. Type any item in that category as your first guess. The game shows you the lowest common ancestor (LCA) — the most specific group that contains both your guess and the answer. A narrow ancestor like "Canidae" (the dog family) means you're very close. A broad one like "Vertebrata" means you're far off.

The tree visualization updates with each guess, growing to show the branches you've explored and narrowing down where the answer must be. Use each guess strategically — start broad to split the tree, then drill into the revealed branch. You have 20 guesses and a time limit, so accuracy and speed both matter. The best score is guessing it in 1.