Invaders

The jars on the Slopwright’s top shelf climb down the pegboard in rows, with sardine tins and thimbles, and march on the bench: “The jars on the Slopwright’s top shelf have climbed down in rows. You have a ruler, a rubber band and four pads of sticky notes.” The launcher is a rubber band on a fork, riding a steel rule along the bench edge; the shields are four sticky-note pads, which wear away where the slop drips on them.

Every wave comes in a different shape, lower and faster, and from the third some jars are sealed and lose their lid first. A paper moth crosses the top now and then, worth a mystery amount. A bot played a few thousand games first, to prove every wave can be cleared before it lands.