Earth is one HUGE Killing field.

Lets pretend that I'm god.

I have a blank slate and I want to create a world.

I'm omnipotent and so I can create whatever I want, however I want.

I choose a system that is based on eating. Everything has to eat in order to survive.

I then make it so that every living thing on the entire planet is also made of food.

I create an enormous killing field where everything is killing and eating everything else, often in horrendous and terrifying ways. Some creatures eat other creatures alive. Some wrap others in cocoons and inject them with a poision that melts them so that they can then be drunk. One animal keeps it's prey in captivity and then kills and cooks it over fire. Often in the company of friends while laughing and drinking.

I gotta say. If you can create anything that you want then that's a pretty sick system to come up with.