I found this games by chance and now they are one of my favorite puzzle games.
It took me about 1 hour to do this but its ok.
Here is an image of the WHOLE map, yeah I checked every single square on the entire board to do this, looking for another secret place (it took me about 1 hour to do this but its ok).
Now waiting for the sunkeen city secret and checking all others games if they have or not a secret on it.