According to WebMD, here are some signs to watch for:
"Here’s what to look for in yourself or someone close to you -- your partner, a child, or a friend. You need to have five or more of these signs in 1 year to have a problem, according to criteria that were proposed in the DSM-5:"
Thinking about gaming all or a lot of the time
Feeling bad when you can’t play
Needing to spend more and more time playing to feel good
Not being able to quit or even play less
Not wanting to do other things that you used to like
Having problems at work, school, or home because of your gaming
Playing despite these problems
Lying to people close to you about how much time you spend playing
Using gaming to ease bad moods and feelings