Installing Unity Web Player in 2019

So you came here looking for how to install Unity Web player in 2019 on Chrome, Firefox or Edge. The basic answer here is that you shouldn't do it (see: disclaimer) but there are a few ways to make it happen if you insist.

here's what a Unity Web Player game looks like in a modern browser.

Disclaimer

The short answer is that the Unity Web Player is now obsolete, and my advice is to NOT follow these instructions! They might open you up to hacking, viruses, and more. The best solution is to play browser games that were built with Unity's WebGL exporter. Some of the best indie games are just a click away using web standards compliant WebGL.

Safer Instructions - IE11

If you must play an old Unity Web Player game, the safest way to do it is to use Internet Explorer 11 (which is still technically supported by Microsoft). Unfortunately, Microsoft does not make it easy to downgrade your browser if you already have upgraded to Edge.

it's not their latest browser, this is a screen grab :-)

Less Safe Instructions with Firefox

Another way to do it is to download an ESR version 52.0 of Firefox If you click that link, you'll want to grab the 32 bit version of Firefox for Windows (firefox-52.0esr.win32.sdk.zip). I also tested this with the Mac version (firefox-52.0esr.mac-x86_64.sdk.tar.bz2) and it did work properly.

You'll want to extract that file and run the Firefox executable inside.

From there, you can install Unity Web player using the preceding link.

If you go to play a demo game from the older version of Firefox, it should work after enabling the plugin from Firefox 52:

Here's an example of Chromian Wars running in Firefox today in 2019:

Why Did Unity Web Player Games Stop Working?

For those looking for a little more info, the Unity Web Player stopped working around 2015 when browsers blocked something called NPAPI (Netscape Plugin Application Programming Interface). In the old days it was a way for a plugin to grab greater access to your machine (and run arbitrary code).

Browser vendors universally decided that this type of access was unsafe, and therefore switched to only supporting standards-based HTML.

Unity (the company) responded by discontinuing the Unity Web Player, and building a standard's based WebGL exporter.

Unity WebGL games can be played on this site for free without fear of hacking or viruses!