🎯 Rule Shift Test: Deduce the Hidden Matching Rule

💡 How to play — The matching rule is hidden: you must pick the card that matches the reference card by colour, by shape, or by count — but you are never told which. Choose one of four cards and you only learn whether you were right or wrong, so the rule has to be worked out from feedback alone. The rule changes mid-test without warning, and the switching points differ every game. Eighteen rounds: a correct pick earns 100 points plus a speed bonus of up to 80, while a wrong pick costs a third of that — so blind guessing averages out to zero. The maximum score is 3240.