Standard Edition (the only edition this time)
Your goal is to make a simulation. Here are some steps to guide you:
Decide what your simulation will be about. What topic will you allow the user to explore?
Think about the rules of your universe. This may be an iterative process, where you will change the rules as your code your simulation in order to make it more interesting or closer to reality.
As this is Processing, your simulation must be a visual one. That is, visual feedback must be provided to the user as the simulation unfolds, just as for the Game of Life, BML traffic model, and Holiday Checkout simulation.
The user must be able to control the initial conditions of the simulation without having to alter the source code. This can be accomplished with mouse clicks or key presses in an obvious way. Provide instructions on screen if you need to.