The goal is to build all four foundations up from ace to king, one for each suit. Below them sit seven piles; only the top card of each starts face up. Click a card to pick it up, then click where it should go — ordouble-click a card to send it straight to a foundation if it fits.
On the piles, cards build downwards in alternating colours— a red six goes on a black seven. Move a whole run at once by clicking its topmost card. Only a king may be placed on an empty pile. Uncover a face-down card and it turns over automatically.
Click the deck at the top left to turn over one card at a time. When the deck runs out, click the empty space to gather the turned cards back up and go through them again — so you never run out of chances, only of moves.
Klondike is famously not always solvable: depending on the shuffle, some deals are impossible no matter how well you play. Roughly four in five are winnable with perfect play, and rather fewer in practice — so if a deal feels stuck, it may genuinely be. Use Game → Deal for a fresh one.