Just use the arrow keys. If you want, click anywhere (not to the project screen) pressing the arrow key you want (it doesn't work in fullscreen mode). This will affect the controling so the Scratch Cat will walk until you click the project screen and press the arrow key you pressed before you stop the walking loop (If you press the opposite key, you will walk left but the objects will go at the opposite direction of the Scratch Cat's direction). I think it's pretty cool (ecpecially the opposite direction walking)!
