My idea was to have something like doodle or die where you evolve the creatures and then afterwards have them "live" in some kind of 3-d world, but have the creatures be goofy 2-d animals, just like the animation. So something like this http://www.pintgames.com/free-games/...Character.html
or this http://epic.drawastickman.com/
I was pointing out a lot of games that have fun creative/evolution elements Ive liked, such as Amazing Island http://youtu.be/AxGFGrM4Kn8
the Discovery game Evolution, SimLife, and my favorite, Googrid. Googrid was the first MMOE, a massive multiplayer online ecosystem. I had some screenshots from about a decade ago that explains how that game worked...
I cant believe I took/saved pictures of this considering how old it is, but here were some of the menus from Googrid to give you an idea of how it worked.
You could customize the pictures in Googrid with anything you wanted, and otherwise you changed colors etc from default bug parts. You would start with a set number of points based off your creature size and then had to allocate them as you saw fit. Brain speed meant your creature could think faster (Ive been bitten! What should I do next? etc. If you had low brain your creature would be too dumb to move. Higher brain meant you could flock, coordinate attacks etc, but at the cost of something else of course.) You also had to time when you wanted your creature to sleep to conserve energy.
The food web worked by having goo(plants) that herbivores would eat. There was blue goo and green goo to have some basic plant competition(you could specialize in blue goo but if seed eaters ate all the seeds and green goo could grow you'd be dead, eventually) Seed eaters eat the seeds flying off from the goos, and meat eaters could actively hunt, or scavenge dead bodies. There were also more advanced things like poison (you could have poison as an herb to make your body indegestible, or my favorite, neurotoxin that slows down the brain so much they can't react to anything).
Something like this could be interesting if the stats were more or less hidden at not as harsh. Googrid had an easy mode that did most of the work for you, but you couldnt fine tune all the cool things.
Here was my world at some point, the little guys are seed eaters, the giant beetles are neurotoxic predators with enough teeth to pierce any defense, but spend most of their time sleeping to conserve energy, only waking up to gorge themselves then sleep again. I also made tiny size 1 creatures with little else but brains and teeth, but complex behaviors like swarming so if one gets attacked all of them attack like bees. They would then gorge themselves on the carcass of the much bigger animal and reproduce like crazy.