Hi Guys
surfing the net, I found this very powerful and above all free game engine
http://xenko.com/features/
I think that the development team can take inspiration from this engine
The software I use? ... Autocad, sketchup, Spazio3D, pconplanner, Kerkythea, wings3d, paint.net, torque3d, AxixGameFactory, PD particles.......maybe blender