Telesto

During the height of the spread of humanoids throughout the system, a team of travellers wanted a planet of their own like many others. This crew of 24 loaded a freighter with enough supplies for a few decades and headed toward this planet with a already strong world tree. Upon landing they began researching their new territory, with no detected signs of life they began building their colonies and spreading across the reaches of the planet. After a few generations the planet had reached a population of about 500. When they reached this goal, they celebrated. Setup a beautiful party around the world tree and celebrated for weeks. These festivities apparently drew the attention of a beast that was slumbering in the depths of the planet. One by one partiers disappeared, people went to go look for their friends never to come back. Out of fear of what was happening everyone moved their camps around the world tree to keep watch on one another. This continued for decades, they found ways to gather supply drops, since they couldn't move, they couldn't gather supplies around the planet. This community became so contained in their own little bubble, some started getting cabin fever and wandering off, never to be seen again. Hundreds of stories arise about what could've taken everyone. They may never know. All they do know is wandering outside the parameters of the tent, means you'll wander into the ghost fields, go mad with the dead, or become one of them. Either way it's all that awaits wanderers.