Do you miss something on BrainKing.com and would you like to see it here? Post your request into this board! If there is a more specific board for the request, (i.e. game rule changes etc) then it should be posted and discussed on that specific board.
Can you put in a Sudoku Chalenge? Not a 2 player game but they can be chalenging. And it could be a timed chalenge keep track of who solves them in the least amount of time or so. Or just something to do while you wait for your oponents to make a move.