weird about your error, i just tested both versions of sonic generations, and both worked fine with -i, i then tried offline, obviously the error is at your end somewhere as all info is grabbed from the rom, it doesnt need an internet connection for anything, cant say about the GUI as never used it, considering 3dsGuy made a super easy/friendly command line app, i dont see the need lol, anyway sonic needs 2.1 firmware minimum if you hadnt got an answer yet