Some older Pogo games require the Java plugin. They were never updated to use the Flash plugin. The <em>regular release</em> of Firefox 52-55 only allows one plugin, which is Flash. The <em>Extended Support Release</em> (ESR) of Firefox 52 will still run Java and other old plugins. More information on this change and ESR: [[Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work?]] How important are those games to you? You could use Internet Explorer for those games and keep Firefox up-to-date.