Netlogo is a modeling environment to model and study complex systems.
File -> Models Library to see library of pre-existing models.
Try out Biology -> Ants.
Info tab explains the model.
Interface tab, then press setup, then press go.
Pressing go again starts and stops the model. Sliders control the simulation speed and model variables and outcomes are plotted.
Code tab shows the NetLogo code.
Getting Started
Help -> NetLogo User Manual
Help -> NetLogo Dictionary