Hey there! I'm a big fan of your Herobook engine (I released "A Vine on a House" a couple of years back), and so when I saw your newest tool I got really excited!
I can see this being a nice little learning aid. It would be interesting to see users push the boundaries of this little tool to create fun art (think tixy). Can you think through other future applications such as animation support? I am not familiar with the language and so I'm not aware of what limitations it poses... but beautiful things do happen when the rules get stretched!
One last thing--I recommend that you add some sort of thumbnail to your tool page.