Players played 18 hours straight with bad results.

We all remember that south park episode make love not warcraft. Even if you are not a south park fan you must have seen it just because it features warcraft. Anyway the plot is that the children stay awake for long periods of time leveling up to defeat an enemy which in the end they succeed at the cost of their health and their image.

While the following event didnt take place on Warcraft although it would be ironic if it did, the new enemy from Square Enix's Final Fantasy XI online takes a solid day to defeat because it constantly keeps healing itself. Some online players took the challenge and decided to play the game until the enemy is defeated. However, after the 18th hour people started feeling sick and were even passing out from playing.

"People were passing out and getting physically ill," leaders of the player guild said in a forum post. "We decided to end it before we risked turning into a horrible news story about how video games ruin people's lives."

Wow talk about gaming dedication the most I've played online 4 hours at the time.

Source