I have been going through the same thing with my son who is almost ten. It started when he was 6 or 7 as well.
The only thing that works for me is to remind him that I deserve the same respect that all the other people around him gets. I also feel like it was a result of overcompensating with things and treats early on. I am a single parent. He also related to adults better, since he mostly associated with adults in our social settings. I was the only parent most times.
Making the transition from treats and things to a more experience based reward system, and taking things away to punish. Time out from lego's and metabots, video games, etc.
And they had to be out of the house, he would hunt for them, and play with them anyway. Especially the gameboy, that is the one thing I never wanted in his life, Grandma bought it for him. That is the one item that has never been allowed since. There are no other gaming consoles allowed either. Nor is hew allowed at friends homes.
My feelings are that they are simply brain-eaters robbing from his own imagination and creativity. Not to mention that "he just sits there for a couple of hours, and hardly says a thing" is not good for them. The screens are small and abd for the eyes, the controls awkwardly positioned and bad for carpal tunnel later in life, and if thats not enough, he acts like a monster when he stops.
Instead, we go places, and do things. When he won't clean up, the toys get put in a box and put in storage. When he's grounded, we are all grounded. And, when that doesn't work, he has recieved a spanking. Not a beating, just a few whacks. I grew up in a military house, and it was common. It seems to be the only thing that he listens to sometimes. Sometimes even that has to happen, and he still won't listen. He still does it, just not as much. I try to be understanding, and ask him to give me the same, put himself in my position, and think about how he would feel, and what he would do.