All the NXTs in the Pinball Machine are programmed used Lego's NXT-G language. NXT-G is the software that comes with the NXT robots. It is a very easy to use programming language that is great for beginning programmers. Commands are represented by icons that are 'drag and dropped' into a program. Very large programs tend to cause the NXT-G environment to slow down and sometimes crash which made programming a challenge at times.
A number of custom blocks are required to run the NXT-G programs that power the Lego pinball machine.
mindsensors.com RCX Motor Multiplexer block
Team Hassenplug's Advanced Display Image block
Each robot has it's own NXT-G program and you can see the programs in the NXT-G files section.