Please create a file .jfkserverrc with a line 'level=' where is one from ${PREFIX}/share/jfk/levels/ or your own and a file .jfkclientrc with a line 'name=' in your home directory. For more information about other variables read ${PREFIX}/share/doc/jfk/jfkserver.sample and ${PREFIX}/share/doc/jfk/jfkclient.sample.