7 Sudoku (more properly Su-Doku, the “way of the exploding number”) is an ancient and mysterious martial art from the Mystic East (Boston). Part of the philosophy behind it is an arcane numerological fortune-telling system. This involves putting numbered tiles onto a 9x9 grid; the sequence in which the numbers fit, the order in which they are added to the board and their location on the grid can somehow be used to generate insights into the future.
The martial art uses attacks to pressure points, usually delivered by a sharp prod of an extended finger. Initiates keep their index finger nails abnormally long. The length of their nails (in inches) is the number of extra dice added to an otherwise unarmed Martial Arts attack, to a maximum of +4. Note that nails even an inch long are conspicuous and may get in the way for many routine actions; some Sudoko initiates are known to have nails up to a foot long, though anything over four inches is generally considered to be counter-productive ostentation.
Sudoku Meditation is a form of numerology in which numbered tiles are fitted onto a 9x9 grid. The rules for this technique are a closely-guarded secret of Sudoku initiates, who refer cryptically to things like “the way of the excluded number”, “the garden of forking paths” and “eliminating the extraneous,” but never actually explain things in a way that an outsider will understand. Successful meditation can give an insight into the past or future, and possibly a vision of things that would otherwise be unknown; the more successes that are rolled, the better the outcome is likely to be, but the details are always determined by the referee. The meditation process takes at least fifteen or twenty minutes (more for a particularly difficult prediction) and involves chanting, fitting tiles, etc. Mystic Power must be used, additional mental attributes are optional.
Initiates train on mats marked out with the traditional 9x9 grid and an (apparently) random sequence of numbers, with a different stroke or combat manoeuvre for each number, and shout the numbers as they leap from square to square. This technique can be used as another way to generate the numerological sequences used for Sudoku prediction, though they require an additional initiate to take notes. One consequence of this form of training is that initiates often shout out numbers and the names of combat manoeuvres as they fight; for example “147 – crouching weasel! 692 – rabid fox!” It’s a hard habit to break, and means that when initiates fight they often seem to predict each other’s moves by extrapolating the next numbers of the sequence.
Such are the perils of reading Thud and the first half or so of Jonathan Strange & Mr. Norrell in the same week...
Update - 2nd nov. I'm making a lot of changes to this, tightening it up and eliminating a lot of repetition. Sometimes I ought to leave things overnight before I post them.