Nice effort! A little buggy, though. I thought it was a little confusing the way I could keep dragging the king/other pieces outside of their normal movement range.
I think it could use a few simple animations to communicate what is happening. I would try moving pieces around and then just suddenly they're dead! Animations can be nice because they communicate what is going on, they're not just for flash anymore.
I found moving the king every turn and then manually clicking end turn was a little tedious. Maybe you could detect when all the pieces have moved and just end the turn automatically? Anything to reduce user clicks is always a thumbs up.
I think this could benefit from sound sound effects! The way I see it, there's two ways you can go with this: 1) the pieces are plastic-y and they make chink sounds as they attack and get attacked or 2) the pieces are basically warriors and you hear the klang of metal on armor when the attacks happen. Not to mention some light SFX when the pieces move. I think stuff like that would add a lot!