Try deleting all of your import statements to awt and swing in your classes. Also try deleting lines of code like "frc = ((Graphics2D)getImage().getAwtImage().getGraphics()).getFontRenderContext();" in your Score class. I think many/all awt/swing methods and/or directly accessing AWT images have no TeaVM/HTML5 translation available which causes it to fail when uploaded to Greenfoot's website. Good luck!