Thou shalt not steal
Test it yourself
Before we begin you can download simple example project, extract it to your server/dropbox and try to run index.html.
You should see something like this:
If you click on bottom text player will be redirected to the original game url address and will see this
and now they can play it from your server.
How does it work?
Security in this example is based on simple comparison of two values
First we check where we are using Browser.URL expression.
If result is true we can start playing. If it's false, we'll be redirected to proper url address. It's simple as that.