Solitaire is the term for a table-top game that can be played by a single player. Most commonly it refers to a card game in which cards are placed into a ‘lay’ according to specific rules – reds on blacks and blacks on reds, in descending numerical order. Cards can be removed and placed into separate piles as long as they are the next card in the suit. The aim is to sort cards into suits, ascending from ace to King. The proper name for this card game is Patience; this specific version is called Klondike.
Of course, the word 'solitaire' is another reference to the theme of loneliness running through the story.
Play klondike online for free here. (free game site, no gambling)