After downloading the LedControl library and extracting it into the Arduino library folder, I uploaded the very simple program for project 22 to my Arduino. The only modification I made to the circuit built in Project 21 was adding the single potentiometer... mine is a 5k instead of the 10k specified which seems to make the response a little bit less reliable... no big deal as I totally understand the program and how it works.
I really have a new appreciation for those old-time programmers who had to code up all this stuff with limited memory, limited video controls, etc... makes all those years play Atari 2600 games seem even more fun.
An 8x8 LED is definitely going to limit what you can do in terms of games, but you can see how a larger display such as the LoL Shield expands your opportunities. I'm now looking forward to learning more about the LCD screen in the next chapter as it has a higher resolution and, apparently, less wiring and coding to get stuff displayed properly. (Reading ahead, I'm hoping that my 16x2 LCD is compatible with the HD44780 driver the author mentions in Chapter 8. Will find out shortly)
Below is a video of the Pong Game... trying to control the paddle with one hand while holding the camera is difficult, so don't laugh at the results!