Not long after the people settled the village, they found really rare materials in the ground nearby.  With the materials, they built a tower to test people and see if they are qualified to become a priest.  The person must climb up webs of ladders and bring a star to the high priest to become a priest.

To download this, go to Twilight World. 
When you're in the world, follow the prismarine path to get to the tower.