Hello
I would like to help you with this one.
I have more than 7 years experience developing software in many fields including medical and video games .
I Have more than 3 years experience with JMonkeyEngine, I have developed 3D video games("University Projects") using JMonkeyEngine and modifying the engine code.
I would Help you with this one, Write full doc and help u through the code, use open-source tools like Blender, Krita , Inkscape and Lmms so you don't face any problem regarding licences and will provide you with the base assets,
I would give you a discount as my primary goal is to build my portfolio.
Message me if you are interested.
Best Regards.