Click on cards on the board that are one greater or less than the number on the top of your card pile. When a card is removed, that card is the new top of the draw pile. If you can't remove any cards, select Next Card to change the top card in the draw pile. Click Take Score when the draw pile is empty and no more cards can be removed.
Scoring: The more cards you remove in a row (a run), the more each card removed is worth. You get 200 extra points times the run length for every card removed beyond the first. Removing the top card in one of the three towers is worth 5,000, 10,000, and 15,000. If you clear the board, you get 1000 for every card left in the draw pile plus a timer bonus worth 0-5000.
Strategy: Plan ahead for those really long runs for a high score. When forced to choose between selecting a higher or lower card, consider both what would make the current run longer AND your ability to make another long run in the future based on what cards you leave on the board. When choosing between two cards of the same value, remove the cards that will expose other cards first. Remember that Ace can be high and low, so 2, Ace, King is a legal run.