You are populating assets in the proper Assets folder for your project right (i.e folder for your current project)? and not the directory where the actual engine is installed? If assets don't show up its becouse of the lack of metadata, i.e .cryasset files. But please use the proper directories for ...
Hello! 5.6.7 version is not complete it do not have good Antialiasing, First Person Character is broken and do not work Waving Flags! By the way Ocean is broken and does not work Snow (it hangs and stops engine)... And by the way FPS are much lower then in before complete versions of CryEngine!I Us...
You should take this up to the developers of Prey, not here. If they wanted the game to be moddable there should be an Editor / SDK available for you to use.