Easthaven Solitaire gameplay is a mix between Klondike Solitaire and Spider Solitaire.
The goal is to move all the cards to the 4 piles of the foundation. Once the cards are placed Ace through King by suit in the 4 piles of the foundation, the game is won. If you cannot make further progress towards this task, the game is lost.
The board initially has 3 cards in each of the 7 tableau columns. The rest of the cards are placed together in the deck. Each of the foundation piles are empty.
Packing, in Solitaire, refers to arranging cards in sequence within the tableau. The rule for packing in Easthaven is that the cards must be descending and alternating color. For example, you can place the 8 of Clubs on the 9 of Hearts. Those two cards can move together and be placed on the 10 of Spades.
In Easthaven, at any time you can deal from the deck onto each of the columns. One card is placed on each of the columns, per deal. The best time to do this is when you can't make any more progress.
Cards can be moved to one of the foundation piles at any time, but must follow two rules. If the pile is empty, the card must be an Ace, or if the pile isn't empty, the card must be one greater and the same suit as the top card of the foundation pile. So the Ace of Diamonds can be placed on the Diamonds' pile only if the pile is empty. The 7 of Diamonds can be placed on the Diamonds' pile only if the top card is the 6 of Diamonds.
The Easthaven foundation is made up of 4 piles of cards, one for each suit.
The Easthaven tableau is made up of 7 columns that initially have 3 cards with the top cards on each column face-up.
The Easthaven deck has 31 cards initially. That means there are 4 full deals and a partial deal of 3 cards.