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 lichess.org
  • 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!