The CORMAS modelling platform is now open-source and available under the MIT licence.
CORMAS (Common-pool Resources and Multiagent Systems; Bousquet et al., 1998) has originally been developed by CIRAD green team to provide a multi-agent framework that can be used to simulate the interactions between a group of agents and a shared environment holding natural resources. It is written in Smalltalk (originally in VW).
You can learn about it in the classroom and play with simulations like an fire agent model or Conways game of life. You can run models and check results in charts. The game of life is explained very nicely.
There is also already a port for Pharo which can be run in Moose images. There is a mailinglist for development. Read more.