The hamster's name is Humphrey, and the cats are Princess (light grey), Cocoa Puff (brown with white spots) and Audrey (dark grey).
You can change the layout of the board if you want. Press the "Stop" button at the bottom of the screen, then the pencil button at the top left, then you can draw in an animal, nut, or floor piece by selecting one from the list at the top. You can also click on the eraser button, and then click on squares to erase the top thing on that square.
Unfortunately, back in 2005, Java applets used a different security model. So to get this woking, you will have to make norvig.com be a "trusted site." I was able to get this to work in Safari, but not in Chrome; I haven't tried other browsers.
If you like this game, you might also like Pugdom, which was done by Juliet when she was 5, with some help from her dad, Peter, and her sister, Isabella, when she was 8.
This applet was generated using AgentSheets® for Windows Version 2.2.5.2 with Ristretto®.