Toy enigma that challenges ingenuity. Solutions to puzzle may require recognizing patterns and creating a particular order. People with a high inductive reasoning aptitude may be better at solving these puzzles than others. Puzzles based on the process of inquiry and discovery to complete may be solved faster by those with good deduction skills. A popular puzzle toy is the Rubik's Cube, invented by Hungarian Ernő Rubik in 1974. Popularized in the 1980s, solving the cube requires planning and problem-solving skills and involves algorithms. There are many different types of puzzles, for example a maze is a type of tour puzzle.
Rush Hour (puzzle) has a solution is PSPACE-complete. This is proved by reducing a graph game called Nondeterministic Constraint Logic, which is known to be PSPACE-complete, to generalized Rush Hour positions. Tromp and Cilibrasi (2004) showed that "Rush Hour" is still PSPACE-complete when the cars are of size 2 only. They also conjectured that "Rush Hour" is still nontrivial when the cars are of size 1 only. Rush Hour (puzzle) Rush Hour is a sliding block puzzle invented by Nob Yoshigahara in the 1970s. It was first sold in the United States in 1996. It is now being manufactured by ThinkFun (formerly Binary