The Gallery presents puzzles created by the Composer application. Several puzzle sizes appear though, of course, the classic 3x3 grid predominates. Puzzles have been chosen for their aesthetic appeal - the degree of symmetry in the initial layout, the number of initially-filled cells (the smaller the better) and the elegance of solution. Puzzles have been categorized according to the most advanced feature to appear in their solution. The Unsolvable puzzles will be of particular interest to developers of computer-based solvers. 'Unsolvable' means that the Solver can't obtain a solution by purely logical means - it has to revert to trial-and-error - not that no solution exists. Like all of the puzzles on this site, Unsolvable puzzles have a unique solution. As the definition of 'Unsolvable' changes with Solver enhancements, the puzzles will be periodically recategorized.
3x3
. . . | 5 2 9 | . . . . . 7 | . . . | 3 . . . 6 . | . . . | . 1 . -------+-------+------ 2 . . | . . . | . . 5 . . . | 8 7 3 | . . . 9 . . | . . . | . . 4 -------+-------+------ . 4 . | . . . | . 9 . . . 1 | . . . | 7 . . . . . | 6 5 8 | . . .
An almost-perfect circle. The puzzle may be solved using Many-Valued Chains.
3 . . | . . . | . . 2
. 9 . | . 4 . | . 1 .
. . 5 | 7 . . | 8 . .
-------+-------+------
. . 1 | 5 . . | . . .
. 8 . | . 9 . | . 4 .
. . . | . . 3 | 7 . .
-------+-------+------
. . 2 | . . 1 | 5 . .
. 4 . | . 8 . | . 9 .
6 . . | . . . | . . 3
The puzzle displays a stunning degree of symmetry - see how many of the initial values are reflected in the bottom-left to top-right diagonal. The very difficult puzzle has to be solved with the use of Many-Valued Chains.
3 . . | . . . | . . 4
. . . | 5 . 1 | . . .
. . 6 | . . . | 9 . .
-------+-------+------
. 2 . | . 1 . | . 5 .
. . . | 8 3 4 | . . .
. 4 . | . 7 . | . 1 .
-------+-------+------
. . 4 | . . . | 8 . .
. . . | 6 . 9 | . . .
7 . . | . . . | . . 3
The puzzle is straightforward to solve. The manner in which the circle surrounds the central cross is very pleasing.
. . . | . 3 . | . . . . . 2 | . . . | 9 . . . 5 . | 7 . 8 | . 1 . -------+-------+------ . . 4 | . . . | 6 . . 7 . . | . 2 . | . . 8 . . 3 | . . . | 2 . . -------+-------+------ . 1 . | 5 . 9 | . 3 . . . 6 | . . . | 4 . . . . . | . 7 . | . . .
The puzzle, which has to be solved with Single-Sector Candidates, features a double circle.
. . . | . . . | . . . . . 5 | 7 . 1 | 3 . . . 9 . | . 8 . | . 2 . -------+-------+------ . 1 . | . . . | . 3 . . . 7 | . 9 . | 8 . . . 4 . | . . . | . 6 . -------+-------+------ . 6 . | . 2 . | . 4 . . . 1 | 3 . 5 | 7 . . . . . | . . . | . . .
Here we see a four-leaved clover. The puzzle is straightforward to solve.
7 . . | . 8 . | . . 9 . . . | 6 . 5 | . . . . . 4 | . . . | 1 . . -------+-------+------ . 6 . | . . . | . 2 . 1 . . | . 7 . | . . 8 . 5 . | . . . | . 3 . -------+-------+------ . . 1 | . . . | 4 . . . . . | 2 . 8 | . . . 3 . . | . 9 . | . . 7
The Solver can't crack this puzzle, which features a diamond, by purely logical means.
3 . . | . . . | . . 6 . . . | 7 6 9 | . . . . . 2 | . . . | 4 . . -------+-------+------ . 4 . | . 1 . | . 9 . . 7 . | 6 . 5 | . 8 . . 6 . | . 3 . | . 5 . -------+-------+------ . . 9 | . . . | 3 . . . . . | 8 5 2 | . . . 4 . . | . . . | . . 1
Another circular puzzle. This one is solved with Single-Valued Chains.