License & credits
This 912-puzzle library uses Keen generation from Simon Tatham’s Portable Puzzle Collection, official archive puzzles-20260923.616da16. The archive and short release identity are verified. The full upstream Git object remains historically unverified; no alternate-source verification is claimed.
Clues were generated offline, freshly solved by the native solver and independently checked for exactly one solution. Both clue patterns and solved grids are deduplicated under all eight square rotations and reflections. Arbitrary value permutations are not counted as valid arithmetic-clue transformations. The source package retains the archive, adapter, validator and provenance. Tools, seeds and answers are not served with the game.
Profiles: 12 four-by-four Easy boards, and 300 each of five-by-five Easy, six-by-six Easy and six-by-six Normal. These are upstream generator tiers, not calibrated human difficulty. The browser UI and arithmetic cover are original code-native geometry, with no external art, fonts or runtime services. Progress stays in a separate browser-local database, without cloud sync.
Upstream MIT license
This software is copyright (c) 2004-2024 Simon Tatham. Portions copyright Richard Boulton, James Harvey, Mike Pinna, Jonas Kölker, Dariusz Olszewski, Michael Schierl, Lambros Lambrou, Bernd Schmidt, Steffen Bauer, Lennard Sprong, Rogier Goossens, Michael Quevillon, Asher Gordon, Didi Kohen, Ben Harris and Anders Höglund. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.