Jarnac in a nutshell
Jarnac is a two-player word game first published in France in 1977. Each player builds words on a board of 8 rows of 9 squares. On your turn you can place a new word of at least 3 letters, or transform a word already on your board by adding letters and rearranging them (RAT + IN = TRAIN).
If your opponent misses a word they could have made, shout “Jarnac!” and steal it. To spot those chances, switch to Jarnac steal mode and enter their board and letters.
Scoring
A word is worth the square of its length, so every letter you add is worth more than the last.
Points (bold) by word length.
FAQ
How do I read the results?
The orange letters are the ones you add. The number is the points gained: the square of the new length minus the square of the old one. Click a word to look it up on Wiktionary.
Which dictionary is used?
The ENABLE word list (public domain, used by many word games), including plurals and verb forms: about 105,000 words of 3 to 9 letters. It may differ slightly from the dictionary you agreed on for your game.
Are my letters sent anywhere?
No. The dictionary (about 320 KB) is downloaded once, then everything is computed on your device.
Isn't this cheating?
Up to you! It is best used for practice, for reviewing a game afterwards, or for settling whether a word exists, with your opponent's blessing.