Icosian game

Invented in 1857 by William Rowan Hamilton the Icosian game is the problem of finding a Hamiltonian circuit along the edges of an dodecahedron such that every vertex is visited a single time, no edge is visited twice, and the ending point is the same as the starting point. The puzzle was distributed commercially as a pegboard with holes at the nodes of the dodecahedral graph and was subsequently marketed in Europe in many forms.