One of Kirby's most favorite games is boxing at the kitty shadows outside the door! I have French doors that are frosted, and have lace contact paper to allow privacy in the upstairs rooms without it being so dark. Kirby loves to box at the kitties he 'sees' through the glass LOL! And he hunkers down on his shoulders and peeks under the door to try and see who's out there. I try opening the door from the outside, and "Kirbstone" will be blocking it! He scared me to death a bit over a year ago, when he was crying in pain, and not able to get around well. I dashed him to the vets in a well padded carrier, and had to leave him there. It took a while for them to get around to seeing him, and by the time they did he was fine! It turned out he had popped his hip out of the socket! It happened one other time, and thankfully he hasn't had any problems since. He needed time to build up his hind quarters as they are his main means of transportation. He leaps 4 feet with no problem, and reminds me of a kangaroo! And he also has crash pads beside the bed to pad his legs while jumping down. He's a very sweet boy!