You can play TicTacToe with this robot. It uses a NXTCam to view the board and then calculates the best move using a MiniMax Algorithm. An IR sensor detects your hand when you drop your ball. The code an more information is available on my blog post.
Already have some of the parts? Use the Build this MOC page to only show the parts you are missing.
Waiting for Inventory to load
Use LEGO Digital Designer to open these files and generate step by step building instructions.