Thank you all for replying. I understand the differing opinions. I probably should have given more information in my first post but didn't want to make it too long. A few things I need to mention.
Regarding his mental health I have been very supportive so far. I got him counselling sessions in secondary school, been to A & E to see the paediatric crisis team, I got him weekly youth services counselling sessions over a year ago, weekly therapy sessions with a qualified child therapist more recently, stopped all pressure about his future education & jobs, don't ask him to do any chores at home again taking any pressure off him. I get involved with his therapist when he allows it at reviews. I've supported him to think about medication anti depressants if he thinks it's worth trying there's no shame in it. I'm honestly really understanding & supportive which even some relatives have said I do too much.
The counselling he quit after 2 sessions, so far he's attended therapy since January but this week cancelled the session & denied it until I found out. He lies a lot, but so do a lot of teens.
The lock down has not affected his life one bit day to day, so that's no reason to extend his gaming times.
I wouldn't say he's mentally 17 in some ways younger. He can't take responsibility for making sure he goes to bed at a reasonable hour, he will stay up all night or not sleep at all just stay on games. He says I can trust him with that but he's proven over & over that I can't. Doesn't follow through to get things done unless I push him etc.
He sneaks the microphone back on with the headset waking me & younger sibling up in the early hours of the morning, again promising he won't. It's unfair to have him affecting our own sleep.
He has anger & respect issues towards me because I make a rule or 2 like WiFi restrictions. He gets very nasty verbally abusive on a regular basis towards me over anything. I get called a cow, bitch, whore etc weekly/daily shouted & sworn at. He makes death threats, has got a knife out before, he stood in the doorway so I couldn't leave the room etc. Police have been round a few times. He went missing for several days & thought it was no big deal! Again police spoke to him.
It's a nightmare to live with, I'm walking on egg shells worried whatever I say might set him off. His younger sibling gets upset too I try so hard to prevent any outbursts happening around them.
He isolates himself, refuses to see any relatives when they visit, won't go out with us. Stays in his bedroom 24/7 apart from to get food, a shower or very occasional walk outside. Letting him have unlimited WiFi for gaming just encourages this behaviour even more, so how is that right to do? He's on it already 12-8 hours every day already without it being on throughout the night also.
I know most other teens are gaming a lot too but they spend a bit of time with their families or friends, doing a few chores, are attending college, have a part time job. My son does none of that, he's in his bedroom gaming instead & this started months before lock down, that has nothing to do with it.
He refuses to do any chores around the house, he used to wash up & take the rubbish out but for at least 6 months it's been a no go. His therapist advised not pressuring him because he can't seem to handle it. So I haven't, he's barely lifted a finger for 4 months now. The only thing I've asked recently is he change his bed sheets but I end up doing it as he won't.
Regarding him moving out, he says I'm the main problem in his life, not unusual for teens to go through a stage of acting like they hate you, but I don't know what else to say or do after 2+ years of this so I say "move out then" he would if he could & asked me how last night, so I said by getting a job & saving money or join the Army as those are ways of doing it. If he googled it he might find other ideas, I don't know but you can Google anything. I'm not being nasty, if he doesn't want to be here then go. I've tried everything I can to improve our relationship, he isn't interested & it's making us all miserable living like this. I've wondered if he has narcissistic personality disorder honestly, but I think his therapist would have said.
I allow unlimited WiFi on his phone at night so he's not left with nothing tech wise, he can also access the mental health apps on it. At least on his phone he will be in bed where he's more likely to fall asleep, also has a blue light filter on his phone which can help with sleeping.
All I can hope for at this stage is that eventually he will get through this stage & hopefully then we can rebuild a relationship. It's heartbreaking for the whole family.