Rrrhuff-That is as self-published German RPG in which the characters are ordinary animals. Even flies as characters are possible.
A character's attributes, life points, and combat values are determined randomly depending on the selected type of animal. There are also several skills that can be gained, but only through training or investing experience points.
Attribute or skill checks are made by rolling a d20 and scoring a result less or equal the character's value. Combat is resolved in the same way with the attacker using his attack value and the defender his dodge value. Damage is subtracted from a character's life points. Every combat phase, a character also loses a random amount of endurance.
The animals played are not quite ordinary animals. While the game is set at the end of the 20th century, animals are quite intelligent, can communicate with other animal species, and even have their own religions.