Plug in Failure

I have a mac, running the latest system OS X El Capitan, using Safari 10.0 and have recently installed Flash Player, version 23.0.0.162. I have repeatedly had a plug in failure notification on a game site called Forge of Empires. When I log in, the icons on the city seem to glow slightly, get distorted and following that, I get a black screen with a plug-in failure notice in the center. I have contacted them and they are not experiencing other issues. I used Firefox and the same issue arise but at least I can send in a crash report. Yet if I launch Chrome, there is no failure.