I'm just going to hazard a guess that that Nick, George and Scott made a very clever decision to set up a script to alert them when HN went up (and perhaps even to submit this post as soon as it happened). This was the first post after the site went up. They might just be lucky, but somehow I doubt it.

Way to hack HN. You win my upvote.

Edit: Also, more specifically to the news of them open sourcing: It'll be particularly awesome if people eventually graduate from learning to code on Codecombat to working on its codebase. Since the backend is all node, it's not inconceivable. A virtuous loop for sure.