// an element of your 8x8 grid
class GalaxyZone {
	public int posX;
	public int posY;
	// things in the grid
	// not the type is a base type, 
	// there can actually be no instances of it
	private List<ZoneItem> zoneItems = new List<ZoneItem>();
	public List<ZoneItem> ZoneItems { get { return this.zoneItems; } }
}

// basic thing that can be in zone
abstract class ZoneItem {
	protected string itemName;
	public ZoneItem(string itemName) { this.itemName = itemName; }
	// all items with have this properties
	public abstract string ItemName { get; }
	// we can get this name for out type, but we main want to override it.
	public virtual string ItemType { get { return this.GetType().Name; } }
}

// start building various types
// keep in mind that you only need a new class if it has 
// properties that are unique to it.
class Star : ZoneItem {
	private int size;
	private float gravity;
	public Star(string itemName, int size, float gravity) : base(itemName) {
		this.size = size;
		this.gravity = gravity;
	}
	public int Size { get { return this.size; } }
	public float Gravity { get { return this.gravity; } }
}

class Planet : ZoneItem {
	private Star star;
	public Planet(string itemName, Star star) : base(itemName) {
		this.star = star;
	}
	public Star Star { get { return this.star; } }
}

// example
GalaxyZone gz = new GalaxyZone();
Star sol = new Star("Sun", 1, 1);
gz.ZoneItems.Add(sol);
gz.ZoneItems.Add(new Planet("Earth", sol));
gz.ZoneItems.Add(new Planet("Mars", sol));