Underground in the desert, there was a big hidden area. In the past, that place had been the ruins of a low-level dungeon. But nowadays, everything had been remodeled—lots of rooms built so a few dozen people could live there.
This kind of dungeon barely existed anymore, since they'd all already been conquered. With almost no dangers left and all the treasures taken, what remained was just an empty shell. Many assassins used these ruins as bases, since over time their locations would get lost.
All across the desert, there were countless ruins of all kinds of levels. The really high-level ones, when discovered, would quickly be taken over by some race, which would then build cities around them to monopolize them. That was because once you entered those ruins, the system activated and gave out rewards for something inside. People called that Secret Quests.
