User blog comment:Bandicootfan63/File help/@comment-3012071-20130720213752

For .def and .cns, you can use NotePad or Wordpad to open them. 7z, you can get WinRAR(Don't worry, it won't expire, it's just really outdated) or 7-zip. And for SFF you can use Fighter Factory. Basically the stuff Plasmoid said.