The Isles
From Overlords 1, "The Isles" were a landmass in the ocean. The Isles were inhabited by a portion of the players, and competed with Tukton until the gameplay slowed. The Isles had a single large house, which had a port for boats. There was also a small pig farm on the north end of the island. The only way to travel to The Isles was by boat or air.
The Tunnels
During settlement, there was an individual who was killed repeatedly after coming near The Isles. Whenever the player would arrive by boat, they were chased by boat until caught. However, the player would eventually dig a secret tunnel approximately 800 meters long that went under the ocean and towards The Isles. The tunnel, once dug, was used by the individual to trespass on The Isles.
Once the tunnel was discovered by an inhabitant, a chase ensued where eventually the trespasser poured lava down the vertical portion of the tunnel - sealing the tunnel behind him, and thus preventing the inhabitant from giving any further chase.