Tic-tac-toe Descriptions

The player (X) plays against the Android App (O). The two players place their mark alternately on a 3 x 3 squares wide playing field. Who sets the first three of his characters in a row, column or main diagonal is the winner. Skill level of your opponent can be adjusted. Idea / theory: https://www.google.com/url?q=https://www.google.com/url?q%3Dhttp://en.wikipedia.org/wiki/Tic-tac-toe%26sa%3DD%26usg%3DAFQjCNHDN9yBMdctdi8LCod4tzL_W2WIJQ&sa=D&usg=AFQjCNGyj6Szi0hgiVxIdvdrcjsOy8vUyw" target="_blank">http://en.wikipedia.org/wiki/Tic-tac-toe