Amazing. This is crazy addictive, especially if you are into games like Sudoku. I played the "easy" levels for a while but recently upped to "hard" and the game became far more complex and interesting. Both modes are great (easy for when I am calming down before bed, hard for when I want a challenge). Like KDR_11k notes below, there is a bug(?) where if you choose a different board size after a match it doesn't actually change the board size - you have to back out to the menu or quit the game and try again. A minor quibble for what is a great, simple game. The simplicity of the rules but complexity of the game reminds me of othello/reversi.