Rubik's Cube, the world's top-selling puzzle game
today i met a 10 years old kid in an elevator, he was quickly rotating the Rubik's Cube. He said he solves it in 35 seconds in average.
in the 80's in the USSR, it was popular among smart young guys, the same that loved programming calculators and computers. i didn't know it was still popular, when there is xbox and the likes!