Hehe, from our point of view, the intro/tutorial needs a lot of work–if you watch the playtesters, anyway. We will continue to work on it.

Most of our libraries and engines and such are listed here: https://github.com/codecombat/codecombat/wiki/Third-party-so...

There are probably a few more in use. If you are really interested, all the code is open source, so you can dig into it here: https://github.com/codecombat/codecombat