If you see “The application was signed with an expired certificate” , here is the only working solution for the 9720:

BlackBerry 9720 , "fixed" games generally refer to Java (.jar/.jad) files that have been modified to fit its specific 480x360 screen resolution or patched to work after the BlackBerry World shutdown. Because the 9720 runs BlackBerry OS 7.1

: Apps requiring a BlackBerry ID or server authentication no longer function.