"Games may be the purest example of technology using operant conditioning." -> You should read Persuasive Technology by BJ Fogg

Fogg is a Stanford professor and founder of the Stanford Behavior Design Lab (formerly known as the Persuasive Technology Lab), and is the guy who taught all the Silicon Valley bigwigs how to create addictive technology that changes people's behaviour.

Persuasive Technology is his book, where he covers the principles of how technology can be used to change people's beliefs and behavior. It was written in 2002, yet it's more relevant today than it ever was in my opinion.

Here are a few excerpts that relate to gaming:

Operant Conditioning in Computer Games

"While game designers rarely talk about their designs in terms of behaviourism, good game play and effective operant conditioning go hand in hand."

"One mark of a good computer game is one that players want to keep playing. <...> Ideally, players become obsessed with the game, choosing it above other computer games or above other things they could be doing with their time."

"Computer games provide reinforcements through sounds and visuals. The rewards also come in other ways: through points accumulated, progression to the next level, rankings of high scores, and more."