Here you can play Tug of War against the computer.

The game develops over several rounds. In each round a coin is tossed to determine whether you or the computer can move the token (the black dot) within the green circle. The game ends when the token reaches the boundary. Your goal is to reach a high value. The computer will push to low values. Can you get a 10?

You can "cheat" by looking at the infinite harmonic function.

You can change the boundary values by pressing 'Reset boundary'.