Icosian game

Hamilton sold his work to a game manufacturing company, and it was marketed both in the UK and Europe, but it was too easy to become commercially successful.

[2] One version of the game took the form of a flat wooden board inscribed with a planar graph with the same combinatorial structure as the dodecahedron (a Schlegel diagram),[3] with holes for numbered pegs to be placed at its vertices.

[5] The game was too easy to play to achieve much popularity,[6][7][8] although Hamilton tried to counter this impression by giving an example of an academic colleague who failed to solve it.

[8] David Darling suggests that Hamilton may have made it much more difficult for himself than for others, by using his theoretical methods to solve it instead of trial and error.

[13][14] At the suggestion of Graves,[3] Hamilton sold its publishing rights to Jaques and Son, a London-based toy and game manufacturing company.

[10][13] This company marketed Hamilton's game beginning in 1859,[4] in both its handheld solid and flat forms,[5] under the lengthy titles The Travellers Dodecahedron, or a voyage around the world, and (respectively) The Icosian Game, invented by Sir William Rowan Hamilton, Royal Astronomer of Ireland; forming a new and highly amusing game for the drawing room, particularly interesting to students in mathematics of illustrating the principles of the Icosian Calculus.

Knight's tours on chessboards, another puzzle based on Hamiltonian cycles, go back to the 9th century, both in India and in mathematics in the medieval Islamic world.

[1] The icosian game itself has been the topic of multiple works in recreational mathematics by well-known authors on the subject including Édouard Lucas,[2] Wilhelm Ahrens,[18] and Martin Gardner.

[12] Puzzles like Hamilton's icosian game, based on finding Hamiltonian cycles in planar graphs, continue to be sold as smartphone apps.