Proposed by Peter Nightingale

Black Hole, also known as Black Hole Patience or Black Hole Solitaire, is a one-player card game played with a standard set of 52 cards. The goal is to play all the cards into the “Black Hole” pile. Initially the black hole has one card, the ace of spades, and the remaining 51 cards are arranged in 17 fans of 3 cards. The fans are face-up, so the value of all cards can be seen at all times. Cards are played one by one from the top of a fan into the black hole. To play a card into the black hole, the card must be adjacent in rank to the card on top of the black hole (and Ace is adjacent to King).

Black Hole was invented by David Parlett [parlett]. A generalised version of Black Hole is known to be NP-Complete [modellingblackhole]. Wikipedia has an illustration of the game and proportion of solvable instances.