Today, I reworked how I calculate the score needed to advance to the next level. Then, I played around in the game for a bit, trying to find some default values that seemed reasonable. I hard-coded the values into the game for the initializing case, but it still writes and reads everything from the options.xml file.
I also updated the main screen to display the name of the game plus the version number. Then, I put it up for review here: Toxic Growth v0.1.0.237 Feel free to download and take a look. If it crashes, most likely you are missing .NET 3.5 or XNA 3.1. which you can get here: