Sudoku (originally called Number Place) is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 sub-grids that compose the grid contains all of the digits from 1 to 9. FEATURES: different difficulties. Hundreds of puzzles for each difficulty. Auto pencil mark (draft).
Chess Strategy & Tactics Vol 1 (1600-2000 ELO)
