Rock, Paper, Scissors
The game “Rock, Paper, Scissors” is well known: two players simultaneously choose one of the three titular strategies. Rock beats scissors, scissors beats paper, and paper beats rock. If both players choose the same thing, it’s a tie.
We can illustrate this with the following payoff matrix, assuming the winner gets a payoff of $+1$ and the loser gets a payoff of $-1$:
Here’s something below the graph.