Game Master (Stardew Valley x Genderfluid OC)

Nikolas was known to be strange. They were quiet, almost silent, as they worked for the Joja Corp. Though they made it aware that they despised their job, they stayed and worked.
One day, they decides to look at the letter their grandfather gave them, and the next thing everyone know is Nikolas gone from Zuzu city.
Nikolas arrives at Stardew Valley in the middle of the night.

This is going to be a POLY relationship between at least 4 people, not a harem.