Try to stay away from the cat using your mouse and the rat will follow kind of buggy when the rat hits the side.
I got the idea and code from a book called Coding for Beginners Using Scratch from Usborne (my virtual pet pico game is also made using that book) 10/7/2023 OH WoW this thing got remixed last week, thanks to qui3 for the remix and the October update! also to DragonNova Qween 765 for the edited remix!