Obviously both would be ideal, but do the rules for playing "with at least one cat" mean a cat as character or a cat as player?

Like is it enough for me to play Archwizard Mittens, the Calico Sorcerer, or do I also need to have rules for my cat sitting down and making a character sheet?

Good question! 

The game jam was created because Lucian knew there were quite a few games/larps were you could play with a dog, but not that many for playing with a cat ❤️

I honestly can't imagine getting any of my cats to create a character sheet, but any game that encourages interacting with a real cat would be awesome!