the .gsa files are Gamebryo Scene Ascii files used to construct the world itself. You either have to have a custom tool to edit them or be lucky enough to have the gamebryo developers suite to use its tools to edit that. The only non static .gsa file is just the school one but the other .gsa files seem to be embedded in some of the bully files. I have been working on a custom editor for these which will allow us to edit the world map data and if I can extract the embedded .gsa files....then we will be able to customise the bully world map.
I will release my .gsa editor in about a week or so.
