It orbited around the sun, uninhabited. Suddenly, asteroids from somewhere impact the planet.
You are what was on one of those asteroids. You control what happens, just don't godmod, or anything. I'll let you know when you do something too powerful/game changing/fun killing. You can also change the weather, and if you develop, you can make civilizations and change the environment. Update your active species with something like this with each post, and say what happened.
I'll start.
A meteorite with moss on it hits the planet. The moss spreads.
-Moss Population: Just a few square inches.
Planet: Hot, humid (You can update this too, just not to major.)
Start with plants/environmental changes. Make it moderately logical.
From the Beetle droppings the COH live in a rich and fertile patch of soil.
-COH Status: Expanding rapidly due to the fact that there is abundant soil and beetle droppings Population: A few thousand Diet: Beetle droppings Pages: « PREV 1 2 3
The other planter causing the ice age passes. The ice and snow melts. Mountains are formed by meteors. The ocean is made into salt water from a huge salt deposit that was in the meteors forming it. Primitive fish form.
The planet orbits towards the sun. The oceans level drops. A desert is formed on the opposite side of the planet. Some beetles migrate there. Some moss evolves into grass.