This weekend I spend some time building a simple game of tic tac toe using an Arduino and a variety of simple components, both analog and digital. Here is a video that takes you through the process of creating this game. You can download the code here. I have left all comments in the code so that you understand how it is built. I am sure there are many ways that this code can be improved and/or streamlined.
Tic Tac Toe Code