My cats do like play fighting, at the moment they are either squabbling over a basket or trying to be top cat on top of the settee. Seeing them running backwards and forwards is great, or hiding under the coats by the back door and pouncing from underneath them as the other one runs past. It can be very funny. But it is only play fighting. They make little purring noises as they chase. Its like they are talking to each other. Leaping over each other. Flying, skipping, jumping. Fun.