On keyboards, use the arrow keys, X (A-button), and Z (B-button).
This is the so-called “chaos game.”
In the three-point version of the game, the user first places a point anywhere and presses the A-button. One of the red, green, or blue dots is selected, and the midpoint of the initial point and this point is plotted. Working with newly plotted point, we iteratively repeat this process.
What picture emerges?