I'm planning to work on the game a bit after the Jam ends, and create a section for the turtle (block the path coming in, go through an ancient ruin with pressure plates to get back out), and mark the spots where you can use the turtle because the turtle was the part people are having trouble with.
To the gated area? You might have gone too far if you tried going to the gate, the intended spot is in the first area above where you see the farm (there are four paths connecting that area but the path leading right can only be accessed using the turtle). It's also possible to get through the area where you eat the sheep using the turtle. And you can press T to flip the turtle over so it stays in place if you need to reposition the dragon. If you need more help on how to progress just ask!
The last section that you missed is where you get to destroy human farms and villages, and the gate you saw at the top of the map leads into the city where you get a boss fight against the Hero...