This is pretty well done so far. I really like how you're able to change the body type of the prey and pred. It's also cool how there's a weight gain system, and you can either have Fen grow in size, or keep all the weight from digestion, even with the feminine style. Though for the latter, if you have them eat a ton of prey, the weight gain proportions get a little ridiculous.
Regardless, this is still turning out to be a really cool game, so I'll definitely keep an eye on this.