It is okay to start a complete new thread for this, because it is a complete new theme, but you can edit the topic name, to give the others a better hint about what your question is about now.

I can't help you with physics, because I never worked with it.

http://www.puppenheim.org/
http://www.wuerfels-welt.de
Old Game Tutorial: http://www.puppenheim.org/MITutorial.zip
Free Game Editor: http://puppenheim.org/AlienalsWeihnachtsmann.zip
http://www.puppenheim.org/blender_starting_main_settings.txt