Yeah, we definitely want to make it interesting. We've made some really cool libraries that make graphics on the canvas really easy to use and pretty intuitive, so you can make cool graphics, animations, and games very quickly.
For example, to draw a circle, you just need to type:
Like Zach mentioned, Khan's CS is a great tool and they have a great team. Our approach is a bit different. Right from the beginning we start with "Karel the dog," which allows you to focus much more on problem solving than on syntax. The dog only knows four commands: move, turnLeft, putBall, and takeBall, so the world is greatly simplified. In this way we are really giving comments on how you take a big problem and break it down.
We've found that starting right with graphics (even though very fun to tinker with) is too large a barrier for many students, since there are too many new concepts at once.
There are a number of similarities. Khan's working on making a very slick tool with a really nice interface to let people experiment with coding.
The focus of CodeHS is much more on the instruction from teachers, and it has more structure. We have tutors that give debugging help and feedback on all programming exercises and projects, so you learn much more about programming style in addition to functionality.
I think Khan has a cool tool, but it's only a tool, whereas we're giving the entire learning experience, teacher included.
For example, to draw a circle, you just need to type:
var circle = new Circle(radius);
circle.setPosition(x, y);
circle.setColor(Color.blue);
add(circle);