Squirrel Eat Squirrel was our first game to have multiple enemies moving around the board at once. The key to having several enemies was using a dictionary value with identical keys for each enemy squirrel, so that the same code could be run on each of them during an iteration through the game loop.
The concept of the camera was also introduced. Cameras weren’t needed for our previous games because the entire game world fit onto one screen. However, when you make your own games that involve a player moving around a large game world, you will need code to handle converting between the game world’s coordinate system and the screen’s pixel coordinate system.
Finally, the mathematical sine function was introduced to give realistic squirrel hops (no matter how tall or long each hop was). You don’t need to know a lot of math to do programming. In most cases, just knowing addition, multiplication, and negative numbers is fine. However, if you study mathematics, you’ll often find several uses for math to make your games cooler.
For additional programming practice, you can download buggy versions of Squirrel Eat Squirrel from http://invpy.com/buggy/squirrel and try to figure out how to fix the bugs.