I'm attemptin to add multiple levels to my pong game. I'd like to simply exchange a few elements with each level, nothing crazy. Just the background texture, the color of the AI paddle (the one on the right side), and the music.

It seems that the best way to go about this is by utilizing the StreamReader to read and write the files from XML. If there is a better, or more efficient alternative way then I'm all for it. In looking over the XNA Starter Platformer Kit provided by MS it seems that they've done it in this manner as well. I'm perplexed by a few things, however, namely parts within the Level class which aren't commented.

/// <summary>
    /// Iterates over every tile in the structure file and loads its
    /// appearance and behavior. This method also validates that the
    /// file is well-formed with a player start point, exit, etc.
    /// </summary>
    /// <param name="fileStream">
    /// A stream containing the tile data.
    /// </param>
    private void LoadTiles(Stream fileStream)
    {
        // Load the level and ensure all of the lines are the same length.
        int width;
        List<string> lines = new List<string>();
        using (StreamReader reader = new StreamReader(fileStream))
        {
            string line = reader.ReadLine();
            width = line.Length;
            while (line != null)
            {
                lines.Add(line);
                if (line.Length != width)
                    throw new Exception(String.Format("The length of line {0} is different from all preceeding lines.", lines.Count));
                line = reader.ReadLine();
            }
        }

What does width = line.Length mean exactly? I mean I know how it reads the line, but what difference does it make if one line is longer than any of the others?

Finally, their levels are simply text files that look like this:

               
....................
....................
....................
....................
....................
....................
....................
.........GGG........
.........###........
....................
....GGG.......GGG...
....###.......###...
....................
.1................X.
####################

It can't be that easy..... Can it?