The organ of the day
Which organ are we looking for today?Which organ is it? Any of them, this time.Which organ do these medicines aim at?
Type an organ. Each guess shows how close its system, region, germ layer, count, arteries and weight are.The whole list can come up, and two more columns: peritoneum and epithelium.Clue 1 is below. Every wrong guess opens the next clue, and your guesses still get the full table.
Your guesses · 0
same close no match ▲▼ higher or lower, heavier or lighter
How to play
Every day at midnight, Zurich time, Organdle picks one organ for each of its three levels. Type the name of an organ, in English, German, French, Italian or Latin, and pick it from the list. The list holds 112 organs and named organ parts, from the brain to the nail, and you can guess any of them on every level.
Each guess becomes a row in the table, like a label on a specimen jar. Every cell compares your organ with the answer: green means the same value, orange means close, an empty cell means no match. A small triangle points up or down: in the region column it shows whether the answer lies nearer the head or nearer the feet, in the mass column whether it is heavier or lighter. A tick marks green cells and a wavy sign marks orange ones, so the table also reads without colour.
Classic picks from the 89 organs most people know or meet early in a course and shows six columns. Hard can pick any of the 105 organs that can be an answer and adds two columns, peritoneum and epithelium. Rx asks which organ a group of medicines aims at: you start with one clue taken from Pilldle’s medicine data, and every wrong guess opens the next one, up to five. Your guesses still get the Classic table.
Hints: in Classic you can reveal the first letter after 4 guesses and the Latin name after 7; in Hard after 5 and 8; in Rx the Latin name after 6. Guesses are unlimited. If you are stuck, “Show the answer” ends the round.
The columns explained
System. The body system or systems the organ belongs to. Some have two: the pancreas is digestive and endocrine, the testis and ovary are reproductive and endocrine, the tongue is digestive and sensory. Green means the same set, orange means at least one system in common.
Region. Where most of the organ lies: head, neck, thorax, abdomen or pelvis, in that order from top to bottom, or the whole body for tissues spread everywhere, such as skin, fat, lymph nodes and bone marrow. The oesophagus, trachea and spinal cord count as thorax, the sigmoid colon as pelvis. Orange is the next region up or down. The triangle shows the direction; there is none when either organ is “whole body”.
Germ layer. The embryonic layer the organ’s main tissue and lining come from: ectoderm, neural crest, mesoderm or endoderm. Hollow organs follow their lining, so the gut is endoderm. Orange means a layer in common, or neural crest against ectoderm.
Count. Single, pair, or several (three or more, or a tissue spread over many places). Green or nothing.
Arterial supply. The main source of arterial blood, such as the coeliac trunk, the internal carotid or the renal artery. Many organs also have secondary sources. Green is the same main source; orange means the two organs share any source, or their main sources hang on the same trunk, or one branches from the other.
Mass. Adult grams. For a pair it is one organ, for “several” all of them together. Green within 15 percent, orange within a factor of 2, compared on a log scale. A “~” marks our own estimate; estimates never turn green.
Peritoneum (Hard). Intraperitoneal, retroperitoneal (primary or secondary), subperitoneal, or not in the abdomen. Orange for the two retroperitoneal kinds, and for intraperitoneal against secondary retroperitoneal.
Epithelium (Hard). The characteristic lining or tissue. Orange inside a family: stratified (both squamous kinds and urothelium) or simple (columnar, cuboidal, squamous and pseudostratified).
Data and sources
Every value was curated by hand from standard anatomy and embryology teaching and checked against Terminologia Anatomica (TA98), Wikidata and the reference values of ICRP Publication 89. Wikidata (CC0) supplies the identifiers, the TA98 codes and the Latin terms. Masses are ICRP 89 reference values for an adult man (an adult woman for the ovary, uterus and breast) where one exists; other masses are published values or our own estimates, and the game marks estimates with “~”. Wikipedia page views helped sort organs into the Classic and Hard pools.
Where textbooks disagree, a choice had to be made, and each one is written down. A few examples: the thyroid’s main artery counts as the external carotid, though the inferior thyroid artery is about as large; the bladder counts as endoderm, with the trigone noted as mesoderm; the testis counts as pelvis, the nearest region. The answer panel shows the notes where they exist.
The Rx level uses a copy of Pilldle’s medicine data, frozen on 21 October 2026. Only groups of the ATC classification that clearly point at one organ are used. Medicines that act all over the body, such as antibiotics, painkillers or insulin, are left out.
External genitalia are not in the game. Organdle is a game for learning, not medical advice. Found a mistake? Write to us at hello@dailyguess.org.
Questions
When is there a new organ?
Every day at midnight, Zurich time, on all three levels. Everyone gets the same organs. The countdown after a round shows the time left.
How do Classic, Hard and Rx differ?
Classic picks from 89 well-known organs and shows six columns. Hard can pick any of 105 and adds peritoneum and epithelium. Rx picks one of 28 organs that Pilldle’s medicines aim at and gives you up to five clues. Each level has its own answer, never the same organ on the same day.
My anatomy book says something else. Who is right?
Possibly both. Germ layers, arterial supply and peritoneal position have cases where books differ, and the game has to pick one value. The section “Data and sources” lists the rules we followed, and the answer panel shows the notes for the organ. If you think a value is simply wrong, please write to us.
Is this medical advice?
No. Organdle is a game about anatomy. The medicines in the Rx level are only there to show where they act; nothing here tells anyone what to take.
How does the streak work?
The flame counts the days in a row on which you finished at least one level. Miss a day and it starts again at zero. It is stored in your browser only.
Can I share my result without giving away the organ?
Yes. The share text has only coloured squares, one row per guess, and a link.
Which languages can I play in?
English, German, French and Italian. You can type organ names in any of them, and in Latin. Pilldle, the medicine game the Rx level links to, is in English.
Anatomy curated by hand; IDs and Latin terms from Wikidata (CC0); reference masses from ICRP Publication 89; medicines from Pilldle’s data. Not medical advice.