This add-on lets you save just your game logic.
Here's a addon I created to save game logic setups. It will save all logic brick settings except things like objects, scenes, text files, etc. You can create menus and sub-menus for the saved logic or use the default menu.
This looks like an excellent addon. It's too bad that logic bricks are not a datablock in Blender like everything else though.
We need developed Blender Game Engine to export our game freely for mobile andoid & ios also desktop linux, windows, osx.
Godot Engine has export templates I think Blender developers can supply for us a BGE export templates. I hope to see it very soon.