Unity web player and Firefox Quantum V. 57

How does it come that it seems to be impossible to play games using the "Web player" using anything else than Internet Explorer? On Firefox Quantum V. 57 (And earlier versions as well) it comes up an annoying message that either try with the browser that computers come with (Internet Explorer/Safari, etc. but NOT Edge??) OR try "Another game". The latter is not an option, all games are unique. For developers, this must be a hard thing unless it is just a configuration issue that prevents the "Web player" to load on Firefox Quantum

 

Because it is deprecated and has been since 2015? It means it may or may not work but if it does not deprecation means exactly that - it is unsupported now and was announced back in 2015 already:

https://blogs.unity3d.com/2015/10/08/unity-web-player-roadmap/

The way to go now is to export for webgl.

 

Then those games should either be ported or removed fom the sites hosting them

 

Ah, my bad, I thought you were referring to games you developed in unity, not other games in the wild. It's up to the devs of those games then, just like e.g. Flash games, etc, not for this unity forum or unity in general ;D

 

You can switch to Firefox Extended Support Release (ESR) to play WebPlayer games.