I need a way to alert users that they need to enable flash with would appear where the content is

[Luke Millard]

Sorry for the long title i will explain a little better so i am working on a gaming website (flash games). On most browsers there is a please enable flash automatically (chrome, edge, ect) but in firefox and possibly others flash is just blocked and thats that there is no message saying that you should enable it. So i was hopping that you guys would have ideas as to how i could do this.