Video game piracy

Not that of any of my upcoming games are unique but I do like to protect my games from being published to other sites without my approval.

The current stencyl publication method is either via Forge or publishing to stencyl/others sites via through swf.

Do we have some basic mechanism to protect our game ip such as site lock? How do we do this?

Yes, site lock can be found under game settings -> loading screen.

What you could also do, is on the loading screen put a small message saying 'Do not distribute'.
I made the mistake of forgetting to site lock one version of my game, I uploaded it to the usual suspects but within a week it had been swiped from those site's and used on many other sites. When I contacted them they all said pretty much the same thing "I didn't know we wasn't allowed to use it"

When I contacted them they all said pretty much the same thing "I didn't know we wasn't allowed to use it"

That defense wouldn't hold up anyway. When you create something, it is implicitly copyrighted by you.

Site-locking is ok to keep Timmy down the street from ripping off your game, but it won't stop anyone running a website full of stolen games.

Your best protection is to hit them where it hurts: ad revenue. If you find your game stolen, file a DMCA notice with their ad provider, host, and the website itself, if you can find a contact for them. The website may ignore it, but by doing so would have pretty much no defense if you chose to take legal action. The host will be forced to remove the page unless the site files a counter-claim. The ad provider would be forced to pull ads from the page (or the entire site, depending on their policies) unless the site files a counter-claim.

The problem is, they can file a counter-claim and you will have no options but to sue them within 14 days, or let them keep your work up. I can almost guarantee you would win a lawsuit, but it would almost certainly cost you more than you would make.