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A game of hangman that cheats while keeping its lies internally-consistent.

How To Play

Play at Guess letters to see if you can find the word

The default configuration, which you can change on the fly using checkboxes, is:

  • Cheat mode on: turn it off to disallow the computer from cheating i.e. make it into a normal game of Hangman. Doing this selectively i.e. mid-game can provide insights into how it works.
  • Transparent cheating on: when the computer cheats, it'll tell you so. Turn this off to make the game feel like it's fair (but difficult).
  • Ghost mode off: Turning on ghost mode will allow you to see, faintly in the boxes, the word that the computer is thinking of. It'll change it's mind as you guess (if cheat mode is on), of course: turning this on is a great way to see how it works.

You can download the full source and run it on any web server (it can't be run from file:// URLs because it uses the Fetch API to download the wordlist).


In 2012, the inimitable Nick Berry derived the optimal strategy for playing Hangman; that is, for the English language, the optimal letters you should choose for any given word length; his approach can easily be extended to suggest the optimal letters for any given game state (e.g. "having a word of this length and having guessed these letters and found them to be in those positions, what should I guess next").

In 2013, I adapted this approach to determine the hardest words to guess at Hangman. In other words: if you know that your opponent will be playing optimally, which words should you choose from in order to maximise the number of guesses the player has to make before they get it. Naturally, this doesn't work as well against a "smart" player who knows that you're trying to catch them out, but it could probably be expanded into a strategy that selectively chooses "hard" words at rate appropriate to the expected suspicion level of the player guessing.

How It Works

This new project, though, goes in another direction: this hangman cheats! Every time a letter is guessed, the game considers all of the words that it could possibly have chosen that are consistent with the statements it's made so far about the length of the word, the number and position of correctly-guessed letters, and the identity of incorrectly-guessed letters. And then, if applicable, it changes the word it was thinking of in order to maximise the expected search space, i.e. to make it as hard as possible for you to guess the word.

Read my blog post about it at


You'll find a stack of constants at the top of cheat.js which configure how the game behaves, e.g. you can tweak the threshold (number of possible remaining words) at which it starts to cheat in order to balance the strength of cheating against the performance of the game (it's not fast!).

I'm considering adding "friendly" features like a PWA manifest (making it "installable"), prettier UI, varied output messages, sound effects (possibly even voice?), etc. But I'm in no hurry, and I'm happy to consider pull requests from anybody who's got more time/energy than I.



This program is free software: you can redistribute it and/or modify it under the terms of the Affero GNU General Public License.

This project includes a dictionary (wordlist.txt) which is in the public domain.


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