public IEnumerable <Wall> Spawn()
{
var walls = new List <Wall>();
var bounds = Context.Bounds;
var left = bounds.Left;
var top = bounds.Top;
var right = bounds.Right;
var bottom = bounds.Bottom - 1;
var width = bounds.Width;
var height = bounds.Height;
// Borders
walls.Add(Wall.Create(left, top, width, 0, Context));
walls.Add(Wall.Create(right, top, 0, height, Context));
walls.Add(Wall.Create(left, bottom, width, 0, Context));
walls.Add(Wall.Create(left, top, 0, height, Context));
// Center
var center = bounds.GetCenter();
walls.Add(Wall.Create(center.X, top, 0, height, Context));
walls.Add(Wall.Create(left, center.Y, width, 0, Context));
return(walls);
}