Most of the applications I build have client designs & data so I must be extremely protective of their materials in all forms. The following game application demonstrates some user interface & logic that is not proprietary.
This set of pages is not an introduction to Sudoku. I will assume that the reader is already knowledgeable, even a sophisticated player. Much of what is presented will not make any sense unless the reader has attempted to understand and solve the hardest logic bound puzzles, the extremely difficult puzzles.
Extreme difficulty will be defined here as puzzles requiring the following array of solution strategies. (examples will be supplied on the following pages)
Extreme difficulty further means that after the application of a strategy in the hierarchy above, many of the previous strategies must be re-applied. Thus several layers of the more complex strategies (i. e. swordfish) must be solved sequentially to arrive at a solution.
Logic bound grids are defined as having a single solution.
The application presented is not a puzzle solver, it is a helper. There are plenty of online puzzle solvers. By helper I mean the application implements my particular solution process.
In addition, the application allows the user to re-engineer puzzles for different looks. This permits the re-use of an extremely difficult grid in many different forms. This becomes important once a survey of online puzzles has been completed. I only found 18 unique extremely difficult grids online. Not only can one re-engineer puzzles, more aesthetically pleasing, symmetric puzzles can be assembled (see examples).