Example of tile level construction in C# - overly simplified, quite useless and completely untested

TileBuilder.cs

public Tile tilePrefabs[];
public int width = 1, height = 1;
public Vector2 tileSize = new Vector2 (1.0f, 1.0f);

Tile tiles[];


void Start ()
{
	tiles = new Tile[width * height];
	for (int y = 0; y < height; y++)
	{
		for (int x = 0; x < width; x++)
		{
			SetTile (
				x,
				y,
				Instantiate (
					tilePrefabs [Random.Range (0, tilePrefabs.length)],
					transform.position + transform.right * tileSize.x * x + transform.up * -1.0f * tileSize.y * y,
					transform.rotation
				)
			);
		}
	}
}


public Tile GetTile (int x, int y)
{
	ValidateCoordinates (x, y);
	
	return tiles[y * width + x];
}


public void SetTile (int x, int y, Tile tile)
{
	ValidateCoordinates (x, y);
	
	tiles[y * width + x] = tile;
}


void ValidateCoordinates (int x, int y)
{
	if (x >= width || y >= height)
	{
		throw new System.ArgumentException (string.Format ("Tile {0}, {1} is out of bounds ({2} x {3})!", x, y, width, height));
	}
}