Now that your game is working, you might like to try using most of the same code to create different games. (I suggest that if you make changes, you save it to a different file, so you don't lose your current game.) In particular, you could change nexttarget() so that it asks a question and gives some possible answers, and the player has to choose an answer as quickly as possible. Alternatively, you could create a Simon Says style game, where the game gives a sequence of buttons that must be pressed, and the player tries to repeat it.
If you have an Internet connection and are feeling adventurous, you could try using your controller to play your Angry Birds game from the previous chapter. Search the Internet for ScratchGPIO to download an enhanced version of Scratch, and try to explore how it can interact with the Raspberry Pi's GPIO pins.
If you're interested in learning more about electronics and what you can do with GPIO, take a look at Adafruit's online tutorials at http:...
