Look at the file headers, just having the extension is a bit meaningless. .SFX is supposedly short for Sound Effects and could mean anything. There might be some standard used in several games. But I am also sure that several people have used the abbreviation for different file formats. .SGG files ...

Hello there! I was trying to hack a quite infamous game just out of sheer curiosity: South Park for the PS1 ported by Appaloosa. I wanted to try take apart the whole game and, maybe, change some resources. I had some luck with videos because they're standart .STR files, which are very well documente...