Kids gotta make their own fun. They pick up all the stuff we leave lying around the house of the world, and play blocks with it as best they can. It's not up to them what kind of stuff they find to play with when they escape the playpen. Crack pipe or Rubik's Cube, they're bound to fiddle with it.
My children are a rock band in my attic. I mean that literally as well as figuratively. I have seen what other parents are subjected to when their children get old enough to make amplified noise, and it ain't pretty. My children are always delightful, and I never get tired of hearing what they play. I guess that means we left the right stuff on the living room floor. Yay us.