okay in the source change the following line
SetErr:End:End SetErr ; allows game to quit if an error is discovered (i.e. missing files)
SetErr:print "missing files" : Amiga : mousewait : End : End SetErr ; If files are missing wuit game and tell us
And see if there are files missing.
Graham hasn't provided the best error checking in the world, so if there are missing files it just quits.