Monthly Archives: December 2019

Puzzle 193: Double Choco

A puzzle to welcome 2020. This is probably not the first Double Choco puzzle you want to solve.

You can find some easier puzzles in the db.


Rules Dissect the grid into regions. Each region consists of a dark piece and a white piece; these pieces are connected edge-wise, and they must have the same shape, up to rotation and reflection. A piece may contain any number of clues; these give the size of the piece. Christmas update: pzprjs release, and introducing the database

It’s still nowhere near where I want it to be, but I imagine some of my readers are in desperate need of puzzles over the holidays. So I decided to finally announce the database – see below. But first:

robx/pzprjs v0.12.0

It’s been a while since I made a proper release for my fork of the pzprjs puzzle applet. Since releasing v0.11.1 back in April 2019, some of the notable changes have been:

  • add 9 new puzzle types: Aquarium, Castle Wall, Compass, Curve Data, Double Choco, Geradeweg, Heteromino, Pencils and Regional Yajilin
  • there’s now a page listing the rules for a type by example of possible errors, e.g. for Double Choco
  • a variety of improvements to individual types, e.g.:
    • Country Road now has a variant rule to permit empty rooms
    • for puzzles like Heyawake, you can now shade-blank across shaded cells (with mouse)
    • Star Battle now allows placing auxiliary dots (e.g., to mark when a star is in one of two cells)
    • Kakuro now supports blank clues
    • for moving puzzles like Herugolf and Satogaeri, movement is restricted to straight lines

Check the Changelog for the full list. Thanks to all contributors, particularly to Lennard Sprong!

At, you can find an index of publicly shared puzzles from all over the internet. In its present form, it started out as a tool for me to keep up with the flood of excellent puzzles shared on twitter. It aggregates puzzle links (to and from twitter and several puzzle blogs, and lets you track which ones you’ve solved, as well as providing some ways to filter (e.g. by puzzle type or author).

If you miss or, this might help fill the gap. Let me know what you think! I hope it doesn’t fall over from the mass of new users.