I bet there aren't half the security concerns that ya'll are claiming there are...
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Hi @Davo5EDF,
I'm afraid you'll lose that bet.
It's common knowledge among informed computer and Internet users that 3rd party plugins are potentially risky. That's why they must be actively maintained with regular security patches & updates. That's also why browser vendors felt plugins were too much trouble for everyone. The major browsers began ending plugin support about 3 years ago with Java, Silverlight, QuickTime, RealPlayer, Shockwave and now Flash Player.
Find another game to play. You'll find plenty of great HTML5 games online. Google is your friend.
Goodbye, good luck and stay warm!