After saving Windemere from famine, King Daniel will grant you an audience.
Meet the King
After feeding Windemere, go to Goodheart Castle, talk to the guards, and request an audience with King Daniel. Milder Flatstomp has gone missing after going to the Darklands. The king agrees to send his men so that Dink can go rescue Milder.
Go north and look for the two soldiers next to the crack in the wall. Go through.
Go to Edge of the World Village
When you emerge from the stairs, go east to the next screen. You will encounter a Stone Giant here. They don't take very many hits from the Clawsword, but they will do a lot of damage if they hit you, so keep your distance.
Go to the fork in the road (where the Stone Giant spawned) and go west. Then there will be another Stone Giant at a fork in the road. Kill the Giant, then go south through the narrow passage where the Stone Giant spawned, and from there, go west. You will pass by a Save Machine, and at the end of the long path you will find a treasure chest.
Go back the way you came, to the Stone Giant in the narrow passage, and go east this time. Keep going east (going north if you get stuck) and eventually you see a roof. Go east a couple of times to find a church. Go in and check on the fountain to drink from it. This heals you completely, and for free.
Southwest of the church, there is a house where you can buy some powerful weapons. Be sure to fight Stone Giants in this area so that you can afford to buy these weapons.
Southeast of the village, there is a Save Machine. There is another machine east of that, but don't use it until you are ready to be transported to the Darklands.
Explore Edge of the World
Now that you have had a chance to heal up, go west from the church to reach the screen with the sign. Use the southeast exit, then go west. Continue going west, fighting Stone Giants, until you reach a cave entrance (it's in the cliff wall at the dead end). Inside the cave, there are two mini-Slayers and some potions and a Golden Heart.
Go back the way you came until you reach the screen with the wooden sign. Go east, stopping in the village to heal up in the church if you wish. Then go west of the village, but not as far as the wooden sign. Go south and you will see some barrels. They just contain normal hearts. Go west from there and you can find some stairs at the top of the cliff. Go down the stairs to meet a guy who will sell you the Hellfire spell for $1500. It's a lot slower to recharge than Fireball, but it's also a lot stronger.
Go west from where you learned Hellfire and you will find more powerups. Many of them are hidden behind things, so look carefully, and burn plenty of trees.
There is a cave at the end that has potions hidden behind rocks.
Outside of that cave, there are three light-colored trees on the left that you can burn. Walk west from there to find the Ice Castle.
Fight your way through the monsters here to meet a wizard. You don't get anything from the wizard except some backstory. But it's worth it to fight the monsters in the castle for gold and experience.
Go to the Darklands
If you are ready, go east from the village at the Edge of the World and check on the machine. Press the red button to go to the Darklands.