Life cycle.

It was a day like any other on Earth, lifeless, with vast oceans and a few small islands that became continents, until out of nowhere, a powerful meteorite attack struck the Earth. But that was a good thing, because those meteorites not only brought more water but also the first forms of life: cells and bacteria. Of all of them, you are the first. Now you can follow the path of evolution and dominate the planet, or simply become a plant cell and make the whole Earth have vegetation. You are free to do whatever you want.