Pretty sure the product is Ratten! ("Rats!") by the German publisher Prometheus Games (who until 2017 also used to publish Savage Worlds in Germany).
Translated pitch description:
Welcome to the world of Rats!, the role-playing game in which players can slip into the fur of a rat and experience all kinds of adventures in the Rat Castle (an abandoned department store).
Although the player characters in this role-playing game are of course strongly humanised - who wants to play real animals? -, they are still rats: they don't walk on two legs, they don't have thumbs and they can't cook very well.
The rats live in clan-like groups - routs - distributed in the departments of the former department store. At the moment there is peace, but this has not always been the case and the danger that old enmities between the gangs will flare up again is always in the air.
It also describes cats as the principal enemies in some other blurbs.
It has been translated into English under the name Packs!