"The best way to pursue happiness is to help other people. Nothing else will make you happier." -George Lucas
True happiness is whatever you genuinely feel good about yourself or the world around you, you can't fake it or buy it, true happiness is the feeling you get on stage or the joy you feel when you win. That is how you obtain happiness, by doing what is right in your heart. Giving to charity, playing with your younger sibling, or winning something all give you a sense of satisfaction.
Finishing something, or getting an unexpected achivement, releases chemicals in your brain, causing happiness and addiction. Two sides of a coin, greatness and evil masked as greatness, and in this century the masked evil is more common.
World of Warcraft and other games like it promote addiction, creating vast, expansive worlds, which become larger and larger with every update. Sending addicts "Continue playing" messages. This is how it has been since the early 2000s. Unlike in the early 1900s, when happiness was described of when family was together, not apart.
This is the definition of happiness between the two centuries, and the difference between them.