The Old World

Geography

Plains
  Wide, rolling plains stretch across vast expanses of land. Rivers and streams wind throughout, creating natural divides and providing fresh water for grazing animals. The occasional lake can also be found.  
Forests
  Forests abut the edges of the plains. Trees are sparse at first and become dense and tall the deeper they grow. Closer to the sea, the forests become swampy and in some places the trees continue growing straight into the ocean.  
Ocean
  The shore might have soft sand beaches, rocky cliffs, or swampy jungle. There are islands, many unexplored. Most of the ocean is unknown to the people of the World.

Ecosystem

Plains
  Many grazing animals live here, and the predators that hunt them. Trees are somewhat sparse, but there are many bushes with various fruits.  
Forest
  There are plenty of forest animals and many birds. Forageable food is abundant, including nuts and berries as well as mushrooms. There are some small springs, but fresh water is a little harder to find than in the plains. The jungles can be very dense, and much more abundant in all regards - including predators.  
Ocean
  Fishing is easy on the shores, and seaweed and kelp can be harvested. There are few predators near the shore, as they tend to live in deeper waters. Like the jungles, predators are much more common in swampy areas.

Localized Phenomena

Plains
  The plains are regularly torn up by tornados and earthquakes. Fissures are not uncommon where the earth has been cracked apart.  
Forest
  Wildfires are normal and healthy for forests. As the Godwar escalates, the fires become more and more devastating.   The jungles are wet enough that they do not burn well, but they do flood.  
Ocean
  Earthquakes happen deep below the waves, causing enormous tidal waves that can wipe out whole islands. These tidal waves also cause flooding and destroy coastal towns.