SET

Every card has four features: number (1, 2 or 3 shapes), shape (diamond, squiggle, oval), shading (solid, striped, open) and color (red, green, purple). The 81 cards cover every combination exactly once.

Click three cards to claim a Set. A valid Set is one where, for each of the four features, the three cards are either all the same or all different — never two-and-one. Spot one, click its three cards, and they're replaced from the deck.

Stuck? Hint glows one (then two) cards of a real Set, but it costs +30 seconds on the clock each time. If there's truly no Set on the table, Add 3 cards deals more (it warns you if a Set was actually hiding). Clear the whole deck to win — fastest time (penalties included) is saved as your best.