There has been some good discussions recently on methods for saving tables and string in image data. I have taken a different approach, parsing the table into a string and then reconstituting it using loadstring(). To demonstrate this technique, I have updated the dGenerator Tower Defence level generator to use the File Manager class to save and load level data (in global data).
Here is a video of the code in action:
The full tutorial is available here: http://codeatuts.blogspot.com.au/2012/09/tutorial-18-saving-and-loading.html
The tutorial includes a dropbox link to download the code. If you have any issues with this there is an alternate code download location here: https://gist.github.com/3805511
Next up we will add the ability to add waves of creeps and finally towers.