Challenge yourself!!! Try out the different form of Sudoku - STAR form. Rules are a little different from the traditional game. Android users can download application from Android market, see link below:
https://play.google.com/store/apps/details?id=com.aaa.sudokujer1&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5hYWEuc3Vkb2t1amVyMSJd
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