We have all played online games at one point or another. Many people play online games on a day to day basis. If you ever doubt that fact, all you have to do is go to your Facebook page and look at all the game requests that you get throughout the day.
I'm certainly guilty of playing online games; currently I'm playing Storage Wars. Facebook isn't the sole choice for online game play. Pogo was one of the first sites designed for playing games. In fact one of my favorite games, the Alchemist, is hosted on Pogo.