The world you are setting here is fascinating, and the animating event conducive to all sorts of potential events and situations. You have everything you need: from a world that has its own rules (food, work, political hierarchies) to interpersonal and moral stakes (the MC's interest in the new comer, the confrontation with an outsider, the sister that will eventually come home...) All I would suggest at this stage is perhaps to find develop a resources that can be used later one to create a variety of scenarios. $crystalBugs, for example, could be a stat that the player accumulates and trades. Similarly, the best friend or new-comer's trust could be quantified and used to give different dialogue options. Things to consider. Good job!