is a generic simulator for various multiagent simulations. It supports developing physical simulations for AI and robotics research with an open-source application framework.
 
SimSpark
One Simulator - Many Simulations
Simulations are created using Ruby and text-based RSG files. Different agents can participate in one simulation, connecting to SimSpark using UDP or TCP.
 
Project Leaders
Joschka Boedecker, U Osaka, Japan
Jan Murray, U Koblenz, Germany
Oliver Obst, Sydney, Australia
Markus Rollmann, Koblenz, Germany
RsgEdit scene editor
Many different bodies
Articulated creatures
Screenshots
Technical Overview
A description of the main ideas of SimSpark  (it’s a bit dated already):
 
O. Obst and M. Rollmann. Spark - A  generic simulator for physical multi-agent simulations. Computer Systems Science and Engineering, 20(5), Sep. 2005. [PDF]
On RoboCup 2007