You’re lucky he still is going to classes and to the dining hall. Sounds like he’s got a serious case of gaming addiction. It would be reasonable to have a discussion with him about setting some ground rules, like lights out quiet time in the room after a certain hour, and basic hygiene issues, such as keeping his grooming equipment put away.
I had a really nice roommate freshman year who was a slob. We just drew an imaginary line down the middle of the room, and she kept her mess confined to her side of the room. It worked, because it was a HUGE room. Perhaps you could work out something like that with him.