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It's much easier now to create an account. Just sign in with Facebook or Google and you're done. We won't use or sell any of your profile information. It's just for signing in and maybe much later to let you challenge your friends.

Anonymous users now see easier puzzles. Beginners were getting frustrated with hopelessly difficult problems. This should help that, but if you liked the harder puzzles or start seeing repeats, create an account!

And I've finished the code migration from coffeescript to typescript. This was a painful change but it should make future development easier and less error prone.

As always, let me know what you think in the forum. Enjoy!

4000 New Puzzles!

I Uploaded the latest batch of puzzles bringing our total to over 14,000! The generator has now gone though almost all the games in the database. I can probably get about 600 more over the next couple weeks but then I'll need more games. I have a bunch from Eric Strange (thanks!) I haven't uploaded yet.

There are also a few minor bug and performance improvements, and some updates on the back end to ease future development. And finally I probably added some new bugs to fix later.

As always, let me know what you think in the forum. Enjoy!

Interface improvements

A few interface improvements for newbies and seasoned players alike. Arrows now show missed capture opportunities and ambiguous moves which should help prevent some confusion. Also there is a new quick move option in the settings page to streamline play. It's quite nice, I'm debating making it the default.

And I fixed a few bugs, including an annoying one where where capture sounds were playing too many times during ambiguous captures. And the puzzle's now make the opponent's moves even after they've been solved which should be more consistent.

As always, let me know what you think in the forum.

Lots of little changes

Thanks to Kukaburra for many of these suggestions! And to Lloyd for noticing and telling me about a bug before any serious damage was done. Deleting comments was also deleting problems!

  • Added cheaper yearly subscriptions.
  • Added subscription status page with privacy settings for premium users.
  • Added number of correct attempts and average rating of mistakes in problem review.
  • Main site should now sync name and email changes to forum.
  • The users index is now filterable to only active accounts.

As always, let me know what you think in the forum.

More Customization Options.

Thanks to Bob Newell for this suggestion! Definitely check out his Checkers Webzine if you haven't already. Anyway, the settings page now has a few more options for tuning the look and feel of Checker Cruncher. You can turn off the board's algebraic notation, numbered board, and perspective effects if you don't like them.

I do recommend leaving the numbered board on unless you are very used to the checkers notation, especially when playing from the top. Otherwise it's easy to get confused on which way your pieces are moving and hard to follow the analysis in the comments and engine lines.

As always, let me know what you think in the forum.

Comments and Customization.

You may have already noticed the new board colors. There are new options available for board size, color, piece set, and difficulty available on the settings page. My personal favorite is the original pieces on the vinyl board, but check it out, you might prefer the wood pieces or the marble board. With the infrastructure in place it's easy to add more sets so if you know how to draw and want to contribute, shoot me an email.

You can also now vote on individual puzzles. Voting helps me find and disable the worst puzzles and helps other players find and enjoy the best ones. I may also add personal favorites pages if there is demand, it would be easy to do.

And lastly, comments are a place to help yourself (by asking questions) or future puzzlers (by answering them). They aren't shown until after the attempt is made so don't worry about spoilers.

Questions that that might spawn long threads, like pointing out puzzles that should be removed are probably better placed on the forum. But interesting lines or confusion about a defense or just simple comments are all welcome right next to the puzzle.

I'm planning on allowing mini-boards in the comments to make posting variations easier. But that looks tough to get right so it might be a while and I wanted to release what already works.


Over 10,000 puzzles!

The problem generator has now seen several rounds of improvement and it's finally in a pretty good place. I like most of the puzzles it builds and I'm going to need some time looking at them and getting feedback before I'm able to improve it further.

I've left it running all week so as I write this we have over 10,000 puzzles. That means we have a wide range of difficulties available and nobody should be seeing a lot of repeats for a while. After the ratings stabilize a bit I'll add the next batch.

As usual, the new puzzles don't have an established rating so until they get sorted you'll see some puzzles that are too easy or too difficult. Every time you get one of these you're improving the site for everyone else by helping to sort the puzzles.

Thanks and good luck!

Big update

Three things came together all at once!

Below are a few details, as always, try these out and let me know what you think in the forum.

1) The problem generator should build fewer problems with too many alternate moves, especially in long capturing sequences. It should also be smarter about ending promptly when you find the answer instead of asking for a extra move or two. I had built over 1000 new puzzles but a discovered bug left me suspicious about their quality and I had to delete them. It's fixed and running again so a bunch more are on the way very soon.

2) We now have an android app! It works the same way as the mobile web page but there is a lot more screen space available. You can opt-in to the beta here. It works pretty well for me but I'd like some more data before pushing it out to the public app store. The iphone version is tougher because of their store policies, let me know if this is a priority for you.

3) And lastly, as requested in the forum, you can now support Checker Cruncher's development and server costs by subscribing to a premium membership. If you enjoy Checker Cruncher and want to support it this is a great way to do so. Check the membership page for details, or the supporters page to see who's already there.

Thank you and enjoy.

Yet better problem selection

A couple of improvements for me and for you!
  • Users should be less likely to see problems repeatedly.
  • I changed the start next problem from a form submission to a link so you can now bookmark or navigate directly to it.
  • I Fixed a bug causing crashes on phones when the session expired.
  • I Added better logging, crash reports, and email notifications to the backend. Which should help tracking down issues more quickly.

5000 Problems!

I've made some minor changes to the problem generator to try to improve the tactics puzzles that it builds. It's been running near continuously for a week and built another 2378 puzzles putting our total over 5000!

Try the new puzzles and as always, let me know what you think in the forum. This should help users see a greater variety of checkers positions though more improvements here are coming.

Note that the new puzzles all have a rating of 1500 regardless of how difficult they are and who they get served to. So expect to see some puzzles that are too easy or too hard for a little while. They'll sort themselves pretty quickly. Enjoy!

Better problem selection.

Over the last few weeks I've experimented with a couple different methods for selecting problems. The first attempt looked for puzzles with ratings around a relatively large standard deviation from the user's rating. But some puzzles were trivially easy and offered few rating points even if correct which some users found frustrating.

The second attempt shrank the standard deviation and added difficulty settings to allow users to choose harder problems which were now rarely selected. But with the tighter distribution, heavy users were seeing repeated puzzles while new puzzles were not being seen at all given that only some of the users are around the default rating of 1500.

I hope the new system alleviate these issues. The goal is for heavy users to see a larger variety of puzzles and for more users to potentially see puzzles with high uncertainty values. As always, let me know what you think in the forum.

Lots of small features.

  • Piece movement sounds! Taken from
  • Light analysis board features. You can now draw arrows and highlight squares with the right mouse button.
  • Added a small settings page accessible under the account drop down. Change the volume or force mouse movement in case your laptop wants to use the touch screen.
  • Added a couple more sortable fields to the user index page.
  • The problem index page is now sortable by rating and problem depth.
  • See common mistakes and your own previous attempts on problems.
  • Some bugs fixed, others probably introduced.

Mobile Support and more!

  • Touch screens work!
  • Secure http!
  • Sortable and searchable user list.
  • Web interface for admins to shorten or disable problems.
  • Other bug fixes.


CheckerCruncher is entering public beta! It works reasonably well in the major browsers at desktop resolutions. It’s got a database of 22,000 games, 2700 tactics problems, and 10 friends testing it. There are lots of features I still want to add but the puzzles are both interesting and fun. I’ve routinely found myself playing checkers instead of programming and it’s past time to show it to a wider audience and get some feedback from strangers on the internet. I’m both excited and nervous.

The heart of the site is the problem generator; it scans the database of games looking for problems, builds the solutions, and saves them to the database for users to practice on. These problems are the core experience of the site so every improvement helps. I’d love to hear your feedback both about the problems and the site. I know a little about game programming but almost nothing about checkers so the heuristics it uses are crude and some of the puzzles it builds are ugly.

The worst are the ones like problem 20 with with lots of winning lines, some of which are crushing but the computer wants only the fastest win. Try-again, try-again, try-again, try-again, wrong you lose, is extremely frustrating. I’ll disable these as I find them, point them out on the forum. I can’t give you your points back but I can spare someone else the same pain.

Others like 640 end too early which can be confusing or like 683 go too long ending with a whimper instead of a bang. These types of errors I can’t do as much about yet because they’re so common. Still, I’ll disable the most egregious examples if people hate them.

The best problems (and there are lots of these!) are ones where it gives you the satisfaction of finishing the combination and then ends. Problems like 127 are a joy to play. I think these are great at revealing the depth and beauty inherent in the game of checkers. They’re also fantastic learning tools, my play has improved a great deal from these problems. I hope you enjoy solving them as much as I have building them.

Some of my favorites:

The next iteration of the generator will be more discriminating in the positions it turns into puzzles. This should avoid generating most of the frustrating puzzles with lots of ‘try again’ lines. It will also be smarter about choosing where to end the puzzles. But before I get to building that there are a lot of features I want to add for the current problem set. Some of my ideas are listed below but please share your own ideas, I want to hear them.

Possible improvements in the next few weeks/months.

  • Problems selected by rating instead of randomly.
  • Piece movement sounds.
  • Better mobile and browser support.
  • Better user statistics.
  • Thousands more problems.
  • Showing common errors from other users.
More difficult Ideas that I’ll pursue as time permits.
  • Difficulty settings.
  • Problem comments, tags, and star ratings.
  • Leader boards.
  • Different piece sets.

So that's where CheckerCruncher is at. This site has taken two years to build and I’m super excited to start sharing it. I think it’s already a wonderful learning tool and there are tons of improvements still coming. Please enjoy it and let me know what you’d like to see changed. Good luck!