I’ve been looking for a good definition of a puzzle that is satisfactory to me and have been unable to find one. So I went through the highly unscientific method of reverse-engineering what I thought a puzzle is with my colleagues and came up with the following. But I still think it is missing something. Any help is appreciated.

A puzzle is a game that uses cognitive reasoning (puzzle-solving skills) to get from an unsolved state to a solved state, with some exceptions:

**The puzzle cannot be trivial**: if I give you a picture of a light switch and ask you to solve it, you do not have to use any puzzle-solving skills to flip the only switch that is there. In the same way, Tic-Tac-Toe is not a puzzle for any adult because any adult can “solve” it and tie or win as long as he goes first. This does make the definition of a puzzle subjective for the audience it covers, but making a trivial puzzle and saying it is for toddlers is a cop-out.**A puzzle must involve intellectual effort to get from unsolved to solved.**If the only way to solve your puzzle is by brute force, it is not a puzzle. “Press the right combination of buttons” with no other prompting or clues is not a puzzle. “I am thinking of a number from 1 to 64” is not a puzzle if you respond simply with yes/no, but is a (IMO, fairly weak) puzzle if you respond with “higher” or “lower” and only get six guesses.**Solving the puzzle must be the same as winning the game.**Checkers is a “solved” game. But solving checkers is a different intellectual exercise than winning the game. The goal of solving checkers is to create a strategy that always wins, but winning checkers is about jumping all of the opponent’s pieces. Solving a jigsaw puzzle is the same as completing the jigsaw puzzle.**A puzzle can be generated randomly, but must be deterministic once the player encounters it.**A board of Sudoku can be generated pseudo-randomly, but once the player starts the puzzle, every player that makes the same moves will experience the puzzle in the same way. If you and I get the same Minesweeper board and uncover the same squares in the same order, we will have identical experiences. If you and I play tennis and make the exact same movements, we will have a very different game experience. Chess, unless against an AI specifically designed for this purpose, is not determinsitic. If I make the same five opening moves, five different players may play it in five (or more) different ways. You can make chess a puzzle by giving a set of moves and deterministic rules – there are examples in puzzle magazines where you must mate in X moves with rules for how the opponent will move.