What is the name of this old PlayStation 1 game?

The only thing I can remember was that it was a rat/fox/possum/ferret some kind of animal like that, that killed things. So in the game you were that animal and you got to hold things like knives and bombs and swords. And you could got into these high tech facilities and kill other things and your mission was, I think, to steal things...? I'm not sure. An answer would be appreciated, thanks.