Guides
Guides and Articles
Rules, solving ideas, daily challenge notes, tool guides, updates, and longer thoughts live here.
Recommended
Recommended
Start with these if you are getting familiar with the site.
How to Play Bulls and Cows
Understand A/B feedback, opening guesses, and how to eliminate impossible digits.
Countdown Numbers Solving Ideas
Build toward the target with number tiles, arithmetic structure, and cleaner expressions.
How to Play Futoshiki
Read row, column, and inequality constraints before filling the board.
Index
All articles
Articles are ordered for current usefulness. Future updates, rule notes, and essays can join this same index.
How to Play Bulls and Cows
Understand A/B feedback, opening guesses, and how to eliminate impossible digits.
Countdown Numbers Solving Ideas
Build toward the target with number tiles, arithmetic structure, and cleaner expressions.
How to Play Futoshiki
Read row, column, and inequality constraints before filling the board.
How Daily Challenges Work
Play one shared puzzle, submit a score, and compare your result with the same day's players.
How to Use the Daily Archive
Review completed challenge days, winners, puzzle data, and representative solutions.
How Leaderboards Work
Read scores, time, completion records, and the difference between live and archived rankings.
How to Use the Countdown Numbers Solver
Check whether a target and six number tiles have exact solutions, then learn from the expressions.