I think this'd be really helpful if it was documented better. As it is, it assumes you already know what you're supposed to be doing. It tells you part of what you need to do, but buries the rest in the github page.
Some better error reporting, even providing the interpreter in JS (as suggested by another commenter), would allow people to run the app offline without leaving their browsers. Having the ability to install the gem is great, but I would say the browser opens it up to people who might not want to - or can't - do that.
Finally, the layout of the page means you have to keep scrolling up and down to refer to the level details and get back to the editor. There's a lot of horizontal space wasted with the fixed-width layout, when it could be used to present the level details and the editor side-by-side (thus allowing the editor to assume the full height of the browser).
This could be a really good tutorial with a bit more polish :) if I understood it all and knew Ruby well enough I'd gladly contribute.
Some better error reporting, even providing the interpreter in JS (as suggested by another commenter), would allow people to run the app offline without leaving their browsers. Having the ability to install the gem is great, but I would say the browser opens it up to people who might not want to - or can't - do that.
Finally, the layout of the page means you have to keep scrolling up and down to refer to the level details and get back to the editor. There's a lot of horizontal space wasted with the fixed-width layout, when it could be used to present the level details and the editor side-by-side (thus allowing the editor to assume the full height of the browser).
This could be a really good tutorial with a bit more polish :) if I understood it all and knew Ruby well enough I'd gladly contribute.