Multiplayer Sudoku

Sudoku is a logic-based number placement puzzle. The objective is to fill a 9×9 grid so that each column, each row, and each of the nine 3×3 boxes (also called blocks or regions) contains the digits from 1 to 9, only one time each (that is, exclusively). The puzzle setter provides a partially completed grid. In this version, both players simultaneously try to solve the same grid. The one who supplies the most correct missing numbers wins.