Interesting Simulations

Today I want to bring to your attention some really neat simulations that, unfortunately, are no longer available. So, I turn to the Wayback Machine:

World Builder
Creates a map through simulated continental drift, then computes temperature, rainfall patterns, and rivers as influenced by the landforms. Surprisingly, there is no common algorithm out there for simple plate tectonics simulations; this is the only one I've found.

Nation Builder
Simulates the rise and fall of nations, given a map. Simulates some of the factors discussed in Guns, Germs, and Steel, among others. I've never seen another simulation like this one.

Galaxy Builder
Attempts to simulate the rise and fall of intelligent species in a small patch of stars. It's intended to be used for generating a backround for a Sci-Fi RPG, I think, in the form of ruins of past civilizations and artefacts waiting to be discovered.

Nation Builder impressed me a lot. I've spent way too much time watching the animations on the example pages 1 2 3. (The animation on the 3rd page is missing from the archive, probably forever.)(Animation from 1st page temporarily available here, since the Wayback Machine is being temperamental today.)

The World Builder is also quite impressive because, like the Nation Builder, it simulates something that nobody else does. There are lots of fractal terrain generators out there, but none that do plate tectonics. In contrast, there's at least one well known algorithm out there for building solar systems from scratch 1 2 3.