After opening the locked door, I encountered one goblin bullying another one. I decided to help him and, in turn, he told me where the goblin king is. In order to get to him, though, I had to defeat a Gelatinous Cube. The king was quite easy to beat, so this means I explored the first level of the tower. He gave me a key to the next level and promised me he won’t attack the humans anymore.
I got to the next level and activated the teleporter. Then I decided to go back to town in order to upgrade my equipment, turn in some side quests and complete some additional ones. I also got a few side quests for the next few levels. This is where I stopped playing.