Solitaire is, as you'd suspect from the name, a game for one person. However, it is possible to play a version of the game with two players. Two-man solitaire is very different from single-player solitaire. Not only does it add a player, but the game becomes one of fast thinking and quick action.
Sit across the table from your opponent. Shuffle your deck of cards, and deal out a standard Klondike solitaire opening board: seven piles, first with no face-down cards, then one, then two, all the way up to six face-down cards. Each pile should have one face-up card on top of it.
Face your opponent, and once both of you have boards set up, count in unison: "Three, two, one, go!" At the moment you say "go," both players immediately begin playing solitaire. When you have to turn over new cards, you must flip three at once.
Make two piles in the center for each suit, instead of one. This will allow enough space for all cards to eventually be played in the center.
Play your aces at the top of your board as normal. Even if your opponent has played an ace, there will be room for a second pile.
Play any other cards onto either pile in the center as normal. For example, if you have to play a four of clubs, you must play it atop a three of clubs on the pile. If both piles have a three of clubs showing, it doesn't matter which pile you play it on.
End the game as soon as one player has used up all the cards in his deck. That player is the winner. If the game stalls and neither player can play, take the top card of your flipping deck and place it on the bottom, then continue play.
You'll have to trust your opponent to follow the stacking rules on his side of the board, since you'll be too busy to watch him.