Reversi

The rules of Reversi (also called Othello) are very simple
The goal is to flip your adversary's pieces over to your color by bounding them with your pieces
You may place a piece on an empty space neighboring to an opposing piece so as to form a line—orthogonally or diagonally—of contiguous opposing pieces that terminates in a binding friendly piece.
You must place the piece so that an opponent's piece, or a row of opponent's pieces, is bounded by your pieces. All of the opponent's pieces between your pieces are then transformed to become your color.
When you place a piece in a valid space, all opposing pieces between the placed piece and a same colored piece are flipped.
The object of the game is to own more pieces than your adversary when the game is over. The game is over when neither player has a move (board is full).

You can capture horizontal, vertical and diagonal rows of pieces. Also, you can capture more than one row at once.
There is three difficulty levels and hints.