I don't write too many classic sudoku; in part because it's challenging to make them stand out from all the computer-generated sudoku out there and in part because there is simply no market that "pays" for classic sudoku because the random scatterings of digits from a PC are essentially free.
Still, I do enjoy exploring different classic sudoku themes, and making challenging puzzles that only require "simple" steps. Fortunately every year I write 7 puzzles for the Silicon Valley Puzzle Fest tournament (my previous years' puzzles can be found here, here, and here). This week's Friday Puzzle consists of the puzzles that were highlighted last weekend. This year I tried to make some slightly harder puzzles while still exploring interesting geometries and some unusual themes. I particularly like "Missing Digit?", but I think the solving paths of other puzzles like "Button" came out really well too.
The winner - James Wilson of San Francisco - averaged about 5 minutes on each of these puzzles including the final, so use that as your par time if you want to play along at home.
Rules: Place the digits 1 through 9 into the empty cells in the grid (a single digit per cell) so that each digit appears exactly once in each of the nine rows, nine columns, and nine outlined 3x3 regions.
Adult Round Puzzles: