Java Applets

This site has many Java applets. A Java applet is a program that is downloaded and run on your browser.
Java applets must be signed to have permission to run, because security.
Signing an applet requires a certificate.
A certificate costs about $200(US) per year.
So the applets here are unsigned.

Java Blocked is Oracle's explanation and workaround, and the dangers of running unsigned applets (it's risky!).
Oracle is the owner of Java.

It is possible to run unsigned applets. Here's how:

You should go to www.java.com and download the new java whatsit there.

Then go to Control Panel (in the start menu, or wherever windows 8 puts it), and:
Click: Java
Click: Security tab
Check: Enable Java content in the browser
Click: Edit Site List
Click: Add
and type this in the little box: https://www.hexatron.com

Click: OK until there are no more OKs to click.

Following these directions will subject you to vague menacing threats.
The browser will still complain about running an unsigned applet, but should permit running applets.