Doubleback

This ROM cartridge game challenges the player to draw circles around objects which pop up on the screen.

Your joystick steers the head of a constantly moving line segment, which by circling it back upon itself, you can make into a loop. Capture an object within that loop, and you score points. Objects continue to appear on the screen, and stay until you circle them. Capture more than one object in the same loop and your reward is multiplied.

The difficulty of the game is in avoiding the objects. Your line segment can run into itself and the edge of the map, but not one of the objects you're trying to circle. That ends your turn. Play becomes a trick of turning tighter and tighter circles to capture objects before they disappear, but not too tightly as to run into them. You can vary your speed, and correspondingly the length of your line segment, by the distance your joystick is from its center. The result is that at maximum speed and length, your line turns widely.

Further increasing the challenge is that the objects move. Apples and cherries are nice and stationary, but the magnets drift slowly. The roller skates skate. Then the yo-yo's appear, doing what yo-yo's do. Timing becomes important. The final complication is the skulls. They're worth no points and they don't go away until you crash. You just have to dodge them and keep circling the moving objects. Hot seat play for two players is possible, giving you the opportunity to laugh at someone else for their inability to draw a circle.