This grid of LEDs has 8 inputs (think rows) and 8 outputs (think columns). By controlling the signal on the wires you can light one or more LEDs. By turning lights on and off very fast you can use persistence of vision to produce images, animations, and even games.
See the attached picture for dimensions of a similar LED grid, or the 3D model.
Note that on one side there is a small round bump. This is to help you figure out where pin 1 is located (so you can’t install the grid backwards).
Move a dot using a joystick (sold separately)
Play tetris using a joystick (sold separately)