Assuming they've only been playing for a day it could again just be illness. At any rate I doubt they like us having a gigantic derail debating their physical and psychological state, so maybe we should stop this before it gets out of hand.
It pretty much should have ended after I pointed out that the definition of "addiction" isn't nessisarily "drug, I would sell my mother, addiction from hell".
You are correct in that drug addiction is not the only type of addiction. However, behavioral addiction (ie addiction to video games) isn't commonly associated with psychosomatic symptoms. Meaning, people who are addicted to gambling don't necessarily feel sick when they don't gamble, they just find the urge to gamble impossible to resist. Real, physical symptoms only set in when the addiction has progressed so far that the sufferer is so obsessed with their behavior that it has actually impeded their health in a physical way- for example, playing so much Terraria that you forget to eat or drink. We can safely assume that someone who is so obsessed with a video game that they're starving to death isn't going to take a break to post on a forum "Hey guys, I feel like I'm starving to death! Time for more Terraria!" It's much more likely that, as others have said, Levi is just catching a cold and being immersed in a game is distracting him from those symptoms. I've had a sore throat all day, but I've barely noticed it in the five minutes I've been focused on writing this post. Does that make me addicted to post-writing?
Sorry for continuing the derail, but addiction is a really touchy subject for me. And a lot of people, which is why the thread derailed in the first place. I don't want to clutter up the thread any more, so I won't respond to counterpoints here; if you really want to discuss it further I'd be happy to do so in a PM.