X-Sums

Updated on (created ) — Filed under: List Matúš Demiger Paper Ported Puzzle Zuzana Hromcová dohz numbers piece

The original X-Sums rule, that forms the basis of this genre, can be traced back to the SUDOKU 8X8 LMI contest, by Zuzanahromcová & MatúšDemiger. This was followed shortly by two addtitional puzzles: one by Bram de Laat and another by Richard Stolk.

In 2020, Jonas Gleim made a X-Sums puzzle for the Puzzle Alphabet competition, which is likely the first standalone X-Sums puzzle.

In 2022, dohz formed the first full X-Sums puzzle set. Inspired by this classic set, Pedro added arrows plus some extra cursed puzzles, while creating this interactive app (2023), using the Kudamono Editor.

Each puzzle has a single, unique solution.

loading... puzzle1 loading... puzzle2 loading... puzzle3 loading... puzzle4 loading... puzzle5 loading... puzzle6 loading... puzzle7 loading... puzzle8 loading... puzzle9 loading... puzzle10 loading... puzzle11 loading... puzzle12

This small example by PinkHoodie clarifies the behaviour of absent cells:

loading... puzzle13

This series uses empty arrows inside the board, thereby giving no number clue away. It can be considered a small cursed expansion to the original, classic ruleset, which did not bar this possibility.

loading... puzzle14 loading... puzzle15 loading... puzzle16 loading... puzzle17 loading... puzzle18 loading... puzzle19 loading... puzzle20 loading... puzzle21

In addition, here's some bonus questions (idea by dohz):

loading... puzzle22 loading... puzzle23

The zero variant was first used in a standalone X-Sums puzzle by Jeffrey Bardon (IHNN).

Here's a set of puzzles by dohz using this variant:

loading... puzzle24 loading... puzzle25 loading... puzzle26 loading... puzzle27

And a puzzle by PinkHoodie:

loading... puzzle28 loading... puzzle29 loading... puzzle30 2023-04-13 Extensive thanks to dohz for transcribing the classic set (and adding a new puzzle!), for thoroughly checking the cursed set! 2023-04-15 Thanks to dohz for making this page and implementation tremendously better! 2023-04-16 Thanks to Freddie Hand (Puzzle Maestro), Jonas Gleim , Lennard Sprong (X_Sheep), Martin Ender (Menderbug), David Altizio (djmathman), Jeffrey Bardon (IHNN), Tom Collyer for help tracing and understanding the elusive origins of this genre. 2023-11-04 Fixed a regression found by dohz (cause: incorrectly set mode at startup) 2023-11-05 Restored correct grid/frame drawing (external lines no longer shown); added slightly better hotkeys for arrows 2024-01-20 Variant zero added to X-sums 2024-01-23 dohz transcribed 4 puzzles using the newly implemented zero variant! Thank you. 2024-01-30 Puzzle Mirror match by dohz was updated to a stronger version 2024-01-12 X-Sums error style updgraded alongside that of Hit Points ヒットポイント 2024-03-10 A cursed puzzle was sent by 5381 - thank you! 2024-03-19 PinkHoodie modernised the rule panels for X-Sums, a tricky task. Thank you! 2024-05-24 The particular case of kropki clues outside the grid is now supported, for an X-sums puzzle by PinkHoodie. 2024-05-24 puzzletters PinkHoodie sent 2 puzzles using variants kropki,clues-missing and zero! 2024-06-03 The antiknight variant now considers only inside numbers, as highlighted by PinkHoodie by sending a great test case, and a puzzle! 2025-01-14 External arrows became optional in X-Sums, when axis-aligned, following the global convention for all genres. Highlighting style updated accordingly. 2025-02-10 A small example by PinkHoodie clarifying the behaviour of absent tiles was added - thank you! 2025-03-01 A bug in the external clue range reported by PinkHoodie was patched. Also, PinkHoodie recently re-added missing arrows to the variant puzzles.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.

Cannot load ${fontname} (font)

Please check this url is correct: ../font/FiraSansCondensed-Regular.woff.