Hi there. This little project used to be just a simple CLI tool that I wrote in Ruby while being a student. I recently ported it to work on web instead, so here it is.
The user can set a sudoku board to look like they want, and then press the "Solve a step" button to make Ze Brainz do its thing. When it does, it tries to explain what's happening below the Sudoku board.
Behind the curtains, it works by running a set of algorithms against to either place a number in a cell directly, or to reduce the "helper numbers" for a number of cells.