My stepson has a habit that I feel weird about...

So, I have been with my man for about 2 years and we just had our first child together about 2 months ago. He has another son who is 12 years old who lives with his mom. They are going through a custody battle right now and he does not get to see his son very often. He will be here for thanksgiving weekend though. I met his so. About a year into our relationship and I think he is such a well behaved and well mannered child. Very respectful and affectionate to his new little brother as well. I am still working on getting to know him and spend time with him. His father tells me to treat him like my own son which I try to do. I just don't know him very well yet so it's hard.

Now, his son has ADHD and dyslexia. I used to have ADHD as a child, but dyslexia is a new disorder for me to be around. One thing that sort of irritates me is that he is constantly in his room playing video games or on his iPad playin games. He can't sit still to watch a movie or talk to me. I was raised differently where I would get 2 hours of video game time a day and the rest of the day would be spent with family or doing homework or doing something outside. Now, since he mainly lives with his mom, I sort of believe it is her parenting that makes him think it is okay to be consistently on his iPad or video games. When he was here for fall break we tried to get him out of the house at least once a day, but when we got home he would directly go to his room to play games.

My question is, is there anything I can do to keep him from playing his games all day? Does this have to do with his learning disorder? I want to spend more time with him and feel closer to him. (I'm not very good at video games, especially the ones he plays otherwise I would join him). Should we get some board games or something ?