Toys don't get much more classic than Lincoln Logs: interlocking brown wooden pieces that kids since 1916 have used to build frontier cabins and fences. Under manufacturer Hasbro, Lincoln Logs languished in recent decades. But three years ago, a small company based in Hatfield, Pa., called K'Nex, licensed the brand and found ways to push it into stores. Ever since, the toys have been tumbling into shoppers' carts. With $50 million in sales this year, they're more popular than ever.
But aggressive marketing to retailers is only part of the reason for the revival of the Logs. All sorts of...