Our adopted kitty is approximately six months old. Just in the last week or so, she has been taking to playing in her litter box, jumping into it and digging around, scattering litter and then jumping out, all without any peeing or pooping going on. Today she brought one of her felt mousies into the box and just plain laid down in it! I use non-scented clumping litter and scoop at least once a day. My work desk is in the same room and I do react by clapping my hands and raising my voice to get her out of the box. Maybe she's doing it just to get attention?