Click on either the big cat or the small cat to make it move. The big cat has the alternate code while the small cat has the regular code. Click on the "guide" sprite for instructions.
Useless alternative for the When This Sprite Clicked block, using the hidden hat block from the early Scratch 3.0 previews back in 2018. Not sure where this would be useful but still cool to have a perfect workaround tho.