When my mum had kittens and they were tiny she used to feel sorry for them and worried about them being bored. (they were too young to go out obviously when tiny).
She used to let them play one at a time in the shower cubicle with ping pong balls. They loved it, the balls would be pinging off the glass walls and the kittens went beserk, scrabbling round.
I haven't had a cat for years. I wish people would stop posting these lovely little stories about cats as I am getting broody for a kitten.