Sudoku
Website address: http://www.sudoku.4thewww.com
Completion date: June 2005
Sudoku is a very popular and addictive number puzzle game where you have to solve a 9x9 grid by making sure that every column, row and 3x3 box contains the numbers 1 through to 9.
The site includes a interactive Sudoku Puzzle Solver to solve those tricky puzzles. It also contains a selection of puzzles which you can try. There are also printable grids which you can use.
The site although providing the puzzles for free generates money through the advertising on the site. This is done through partnership with Google Adsense and Text Link Ads.
Through the use of SEO (Search Engine Optimization), this site ranks well in the big popular search engines:
In the above screengrab the site occupys the top two positions when searching for "sudoku samurai". Thats top out of 902,000 other competing websites.