OK, since you're a member now, here are a few questions...
Since you mention multiple beasties, are you thinking of one monster character for a player or are you looking for one player to have more of a GM role and control a variety of beasts?
How inhuman are the beasties going to be? That's really a two parter - #1 physically, are they Star Trek aliens in rubber suits and a few inhuman traits or tentacled blobs, sextupled hairy beasts, and ambulatory plants? And #2, socially, are the monsters organized into basically human societies so the game will be interacting with the monsters on a social level with conflicts ranging from negotiation to outright warfare, or would it be more survival sci-fi where the aliens exist as forces of nature to be survived? (There's also the poorly hidden question in that last one of where the story would stand on non-con. I'm not trying to steer in any particular direction, but my initial reaction to monster sex is more of the violent sort. It's a good idea on it's own, but also fun to subvert it.)
So, where would you want the game to go?