Nerf's Billion-Dollar Toy Empire Surprisingly Started With a Foam-Rubber Rock

Guyer, the inventor who’d come up with Twister, was in his conference room, testing a new caveman game with colleagues. The prototype included a bunch of foam-rubber rocks that, the men soon discovered, were more fun to throw at one another than use in the game. And then something really hit them: “We had inadvertently created the world’s first indoor ball and broken the parental rule ‘no throwing balls in the house,’” Guyer recalled.