Thanks! I believe you can get a very long way with only multiple-choice buttons. An excellent example of this is Brilliant.org. But I'll soon release an "iframe" feature that lets you make your own custom interactions. The iframe is seamless, and can tell TigYog when the user has completed the block, and with which answer.

You own all your content on TigYog. There's no export feature (although you can see the raw content of a page if you replace "/edit" with "/debug"), but it's on my list, and I'd help you export your stuff if you wanted to move the course.

I'd actually never come across Idyll! I'll play around with it and see what inspiration I can take :)