Omg!!! Finally someone knows what I'm talking abot!!! =) My favorite was the rocket dog, I hated the rat king with its bunch of rats... Haha! Really? No wonder it didn't matter how hard I tried I could never complete it... Hehe! I feel better about myself now!
The rocket mouse darting forwards with his pointy tail out infront killing stuff. That game was amazing how it managed to add different character to each different family of animal, how scaried of you the sheep were to how vicious some dogs would be towards you. But yeah see the wiki link, the true ending is ungettable in the N64 game.
Also I remember enjoying how in that game the sound came from speakers in game and if you were close to them it made the rumble pack shake to the beat or you could destroy them for silence in areas. Geo Mod Technology haha.
Fancy hearing me on an amateur podcast with friends gushing over one of my favourite games? https://youtu.be/1I7JfMMxhf8