The game works for me.

Make sure you are not blocking content.

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

One issue that seems more common lately is Firefox's Tracking Protection feature. When it is blocking content in a page, a shield icon will appear at the left end of the address bar next to the padlock icon. This article has more info on managing this feature: Tracking Protection {web link}

Type about:addons<enter> in the address bar to open the Add-ons Manager. Hot key; <Control> (Mac=<Command>) <Shift> A)

On the left side of the page, select Plugins. Make sure the ones you want to use are set to Ask or Allow. ++++++++++++++++++++++++++++++++++++++++ Go to the web page. Once the page is loading, mouse to the address bar and Left-click the icon. Select Permissions. In the menu, Make sure the ones you want to use are set to Ask or Allow.

When I left-click the icon, it shows "Connection is not safe" . No matter how I set the permission or privacy/security the result is the same. When I start Firefox in safe mode, the result is similar except in the screen center there is a small white box with letter "ok" but it is not clickable. I attached two image but it is in Chinese. I hope some one could read it.

This website uses WebGL to draw the game on canvas. It also stores data in IndexedDB (storage), so may not work properly in Private Browsing mode. You can check the Web Console for WebGL related messages. See also the graphics section on the "Help -> Troubleshooting Information" (about:support) page.

I did see error message "indexedDB access denied" in Web Console. How can I fix it?

Are you using Private Browsing mode?

Are you blocking cookies (cookies and storage share the same exception rules)?

I am not using Private Browsing Mode and I enable cookies. After clearing cookies the game run successfully. I wonder whether the memory is full to cause the problem. Anyway thanks a lot for your help.