Outside of a tetris clone, a crappy 2D top-down shooter, and some messing around with stuff like Unity and Flixel, I realize that I have yet to complete a single, polished, bells-and-whistles game. I want to change this, and I have an idea for my next project.

The idea is that you're an amoeba. Amoebas have these eye-like cores (or something like that, I don't know biology), and you have two of 'em. You control one with WASD and the other with IJKL. There has to be a constant radius of stuff around each of the cores:

And the area of the amoeba has to stay constant. So if you move a core in one direction, you increase the amoeba's area, but that increase is compensated by a decrease somewhere else:

Aaaaaand I'd like to implement a vagination mechanic. You absorb things by engulfing them, like a boss. Maybe even an extra core, or a needle that pops you and causes all your inner stuff to start gushing out:

But here's the problem: I don't know how to make this. However, I would like some ideas on how to implement it. Should I explore physics libraries like Box2D? Or maybe something involving fluid physics? Any help would be much appreciated.

P.S. Feel free to steal this idea. I have plenty of ideas. If you do, please tell me how you made it so I can try it myself.