Maybe I've missed it, but in case no one noticed or mentioned it, you can play with two cats at the same time. There are a few spots were the cats are close enough to each other that both play with your choosen toy if you manage to center it in between them. A good spot is at the top of the stair in the starting room. (I don't have any other room type yet, so I don't know if it works for all room types).