Press New game to draw a hidden rule.
Your hand — pick a card to test
Describe your rule guess in plain English:
Rule guess as Python (free, checked every turn):
📖 Rule-guess cheatsheet
Write a Python expression (or multi-line body with return) over:
card.rank (A=1 … K=13) · card.suit ('hearts' 'diamonds' 'clubs' 'spades') ·
card.color ('red' 'black') · card.is_face
mainline — the accepted cards so far, oldest→newest.
Examples: card.rank % 2 == 0 · card.suit == "spades" ·
not mainline or card.color != mainline[-1].color
Guesses are judged by behavioral equivalence (same accepts/rejects on every probe board) —
the exact check the model faced.
🤖 The model's game
Same rule, same deal (starter, hand, draw order). Careful: revealing may spoil the rule.