SUDOKU demo

A demo in traditional style COS

This was written based on a previous trial in .XLS
It is far from being perfect. Rather a challenge for
improvement in all directions (code, interface, ...)
So anyone feel invited to make it better.

USER>d ^SUDOKU5
;; Welcome to this SUDOKU demo !
;; you may solve your SUDOKU easier or create your own
;; under each box entry you find a list
;; of allowed values for this box
;; fill in numbers 1..9 as you need
;; to clear a box enter any character or blank
;; to stop enter . or , for the solver enter ?
;; navigate between boxes by cursor keys <>^v
;;
go: