Oh Effect Games. I was very enolved with this engine and project from it's beginning to it's end. Just be aware the whole source (engine, site tools, etc) is free for any use here: github.com/jhuckaby/Effect-Games . I got the site/tools mostly running on Ubuntu so anyone let me know if you need any assistance.
This was a great engine and site but it's not "technically" HTML5. Effect games used DHTML since it was created before the canvas was a stable taget to develop against.
It was also very cool to create games with the online tools and online IDE; which meant you could develop games anywhere without installing anything. Effect Games is very much missed... <img src="smileys/smiley19.gif" border="0" align="middle" />