Now you can download a first rudimentary version of SeSim, the Stock Exchange Simulator as announced here.
It was tested under Windows and Linux.
You can download the jar file uSeSim_001_alpha.jar which you can run, if java is installed on your computer.
To play around with, create first a strategy, by going to edit->strategies, pressing the "new" button. Chose RandomTraderA and enter some values. Then goto edit->traders and add some traders using your strategy.
And now hit the run button to let them trade.
Have fun and stay tuned, because more updates will follow.