You don't use any specific keys. You just type in what you want and then the rest will play out. Though you will get to choose a few to make the story play out differently.
I give credit to Puppies4ever for making the original version. I will add more over time. I using scratch on December 20, 2014 so I am kind of new. I will add more choices to it eventually. Here are some ideas I have(please comment if you have any more ideas): -being able to choose whether you play as the leader or another cat. -being able to play mini-games -choosing genders -choosing to have kits or not