public GameObject cube;
   public float cubeSize;
   public int sizeX, sizeY;
   int aboutX, aboutY;
   float onX, onY;
     
   void Start () {
    for (aboutX = 0; aboutX < sizeX; aboutX++) {
     for (aboutY = 0; aboutY < sizeY; aboutY++) {
      Instantiate(cube, new Vector3(onX, 0, onY), Quaternion.Euler(0, 0, 0));
      onY+=cubeSize;
     }
     onX+=cubeSize;
     onY=0;
    }
   }