We really appreciate feedback and recorded solves of our puzzles, especially on Logic Masters Deutschland. We post only our favorites there and it's the best place to raise visibility for our puzzles. If you have the time and inclination, we would be delighted if you log your solve there.
Missing Deck Puzzles is the joint effort of two long-time friends, FullDeck and Missing a Few Cards. FullDeck only recently started playing with a complete pack of cards, while Missing a Few Cards used to play with a full deck but is now dealing from a reduced pack. Both have been eager consumers of puzzles of all types since childhood and now enjoy solving and setting sudoku puzzles together.
We are assuming you know the basic rules of sudoku. If you don't, watch the brilliant Cracking the Cryptic (CTC) YouTube channel and you will be addicted within minutes. In our puzzles, we often use sudoku variants including thermometers, arrows, killer cages, little killers, chess constraints, Renban and German whispers lines, Kropki dots, and more. Variant rule descriptions are included with each puzzle description.
In the complete archive, you will find most of the puzzles we have set, with newer puzzles at the top. If you'd rather explore by difficulty, you can jump to a subset of the archive using the links at the top of the page. Every puzzle in the archive has a unique solution that can be reached logically from the starting clues. Each has a link so that you can try solving it in the CTC Sudoku App created by Sven Neumann.
In constructing a new puzzle, we always start with an idea of what we're trying to achieve and a target difficulty level. We brainstorm starting points, follow the logic of that starting point as far as we can, check for solutions, and continue refining constraints and clues until we are happy with the appearance of the puzzle. Then we test it ourselves to make sure the puzzle is uniquely solvable using only logical deductions. Depending on the difficulty level we want, we might add or remove clues. Once we are satisfied, it's time for testing by others. Often that means submitting the puzzle to the CTC testing channel, where other sudoku fanatics test-solve it and provide feedback about difficulty, elegance, and logic. For the mechanics of turning our starts into sets, we use Eric Fox's much appreciated sudoku setting app, f-puzzles, together with additional constraint scripts by rangsk. We then export it to Sven Neumann's SudokuPad app with the solution embedded for checking at the end.
Once a puzzle has been sufficiently tested, we may post it to the CTC Discord server, to LogicMasters Deutschland (LMD), or both. We may also create an easier version (see our description of Brassica puzzles below) to distribute to friends and post here. In keeping with the Hardy-Littlewood Axioms of Collaboration, all of our puzzles are listed as being by FullDeck and Missing a Few Cards, or occasionally as Missing-Deck, regardless of who took the lead on setting the puzzle.
Showcase Puzzles are the ones we are most proud of. They range from easy to ... less easy. We are always happy to provide a hint or nudge if you get stuck. Each of these puzzles has an estimated difficulty based on reactions from solvers in the community.
Beginning solvers might still have difficulty with the "easy" GAS puzzles. We have been setting a series of puzzles for friends who are still just beginning to explore variants in sudoku. These pre-GAS puzzles we have chosen to call Brassica puzzles (Want to know why?)
Cracking the Cryptic introduced the idea of "genuinely approachable sudoku" puzzles, known affectionately as GAS puzzles. These are puzzles that are designed to be at a level that most solvers have a hope of completing even if it takes a while to follow the logic or learn the variant rules.
In the same vein, post-GAS-difficulty puzzles we have chosen to call Indigestion puzzles. Some of the deductions, while logical, may cause brief heartburn, ranging from mild to severe. Each of these puzzles has an estimated difficulty based on reactions from solvers in the community.
Somewhat more intense than mild indigestion are the Heartburn puzzles, which may require more difficult deductions. Intended for more experienced solvers and those seeking a challenge, each of these puzzles has an estimated difficulty of at least 3.5/5 based on reactions from the solving community.
The full archive contains all of the puzzles we are sufficiently pleased with to share. They are organized chronologically by month and year they were created, with the newest puzzles at the top. Every puzzle in the full archive is included in least one Collection, sometimes more.
We love getting feedback on our puzzles! For puzzles posted to the CTC Discord channels, you can provide reactions or post feedback there using links for individual puzzles. You're also most welcome to send email with feedback or to request a hint. If you are asking for a hint, please include a screenshot of the current state of your solution.