What is a puzzle game?

I love puzzle games. I’m not always good at them, but I love them.

I have yet to see the rules or expectations of puzzle games enumerated as such, so here are what I believe to be the basics.

1. Each puzzle must have a single unique solution.
2. The correct solution must be discoverable by pure logic and elimination.
3. The solve must include multiple interrelated pieces or steps.
4. Multiple non-computerized strategies must be available to the player, though they need not be disclosed by the puzzle’s creator.

The classic example of these is Sudoku. A Sudoku, by strict tradition, may not have multiple possible solutions; it is solvable by logical deduction from the given clues; each of the 81 squares is a mini-puzzle of its own but also a piece of the final solve; and myriad solving strategies have been discovered and disseminated since the puzzle’s introduction in 1979. Some of these strategies are quite advanced and rely on well-practiced pattern recognition skills, but don’t require the assistance of a computer. Most everyone agrees that using a computer to solve a Sudoku is not in the spirit of the game. In competition it would be cheating.

Crossword puzzles occupy the sizable gray area adjacent this definition. You could make the argument that they are puzzle games, seeing as how (most, not all of the time) they have a single correct solution and are solved in a series of strategic steps. However, they are not solvable by pure logic. If you don’t know the names of French tennis players or another word for “abounds,” there’s no guarantee you’ll be able to solve the puzzle at all. No amount of logic will save you (I know because I’ve spent too many hours trying to logic out things that are just not contained in the puzzle). I enjoy crossword puzzles, but I will not call them puzzle games.

(The game I recently published, Sootly, is also not a puzzle game, though it comes closer than the crossword thanks to the deductive nature of its clues.)

There is gray area beyond this example as well. For example, the ability of a player to marginally optimize their outcomes at a given game is not enough to satisfy the first rule. A correct solution must be self-evident, all or nothing, not simply a high score that waits to be toppled by a savvier player in the future. Therefore games like Candy Crush, Mini Metro and Scrabble are not puzzle games. From a given starting point there may be a theoretical maximum score that can be achieved, or an actual high score that will never be dethroned. But this is not correctness. Correctness is right and wrong, not good and better. A real puzzle game is not over until you have deprived it of all possible uncertainties. Until there is no conceivable way for your final solution to be topped, even theoretically. Some games attach a stopwatch or move counter to your play session as a way to compare yourself to other players; this is irrelevant to whether or not you are playing a puzzle game and, ultimately, to whether or not you’ve beaten it.

^{I personally dislike being timed. The last thing I want after a long and complicated solve is to be told that I’m not as good as someone or something else. I also dislike high-score lists. There is no version of my life’s story where I become the world’s fastest Sudoku solver—time and genetics are not remotely on my side—so why would I want to know about the person who is? Sheesh.}

To me, the best kind of puzzle game is one you can discover gradually, from first principles. The game’s introduction or tutorial tells you how to verify a correct solution, little more than that. Then it’s up to you to reason, try things out, make mistakes and develop strategies. You teach yourself to play as you go along. When you become an expert at the game it’s because you learned a new way to think, not by rote but by inquiry. And each time you learned a new tool and your perspective shifted, it felt like crossing a barrier. Games like that are a rare pleasure.

Two of my favorite examples—games I keep coming back to and recommending to others—are 0h h1 and 0h n0. I learned to play them in a few minutes. But it took time to become good at them, and every so often I still discover a new trick.

What are your favorite puzzle games?