i found this really really great game called secondlife thats free, you can do almost anything you can do in real life includeing owning a bisness and designing the products you sell, it has its own scripting language to script objects you make in to cars wepons or anything else you can think up.
it is a great game at least give it a try
...secondlife's website...if you decide to play write "zaket pow" in the referal box
thanks
also if you have played it and want to leave feedback or if you have any questions just say so