Here's my two cents....
1) Don't restart. Don't delete. Work from here forward. YouTube is a marathon. If you keep going back to the starting line, you'll never finish it. And the finish line is a successful YouTube channel that enables you to do it full-time.
2) Niche, not mass. Gaming channels are a dime a dozen million. Pick a genre and if possible, a niche within that genre. What genres do you enjoy? Which do you enjoy the most? Which have you enjoyed the longest? Is there a niche within that genre that you enjoy the most? Make that your niche.
3) Once you've decided on #2, look for games that are just about to enter beta that will be in that niche. No game is made in a vacuum. All gaming companies are trying to generate buzz for their games that are in alpha. When you find one that is in alpha that looks like it is right up your alley (the niche you determined in #2), contact the company to see if they will let you into the beta. Tell them that you're a YouTube gaming channel that has specialize in their upcoming game's niche and you are looking for the next big thing and think they might be it. While that will flatter them, it is also true as far as you're concerned. Though they will think you're saying they're the next big thing, you really not. You just said you're "looking" for the next big thing and you think they "might" be it.
4) Start making videos during the beta. Establish yourself as the go-to guy for that game. When they go live, you will then be established and have a backlog of games for new gamers to check out. Do every "how to" video you can think of for the game. One topic per video. Short and to the point. Don't blather. Make every second count. Make a video for even the simplest task. Don't do Let's Play videos during the beta but save that for when it goes live.
5) Try to start a dialogue with the gaming company. They are the key to your success. Get on their radar. In #3, you started that. Don't flood them with emails but email them once a week. Don't email them to just say "Hi!" but be professional and helpful. They're in beta. Their game is thus still in flux. Give them valuable input. Ask them if there is anything they would like to you check out, try, evaluate, test, etc. If you work your relationship right, when the game goes live, they might promote one or more of your videos on their homepage and elsewhere.
6) If another YouTuber is doing the same as you are above, they are NOT competition. They are allies. Give them a shout-out. Make nice comments on their videos. Don't spam their comment sections. Build a relationship with them. Do collaborations with them. The easiest ones are simply challenges. The gaming company wants all of you to help push their game. Show you're a team player. Your goal is to get them to help you become more successful so you help make their game more successful. Double win.
7) The intro video on your homepage is a poor one. Make it 30 seconds to a minute long. Start off with some gameplay but shortly then tell what your niche is ... then tell who you are and why you like playing that niche (people subscribe to people, not channels) ... then tell your release schedule ... and then make a SINGLE call-to-action by asking them to subscribe to your channel. Don't monetize your intro channel. It is an ad. Don't have another ad hurt your ad.
8) Only post gaming videos to your gaming channel. Create another channel and make it a vlog channel. The vlog channel helps develop your following for your gaming channel. Dump all your milestone, viewer mail, "making of...", and such videos onto this second channel. Only produce ONE vlog video a week or even month. Promote it at the end of each of your gaming videos. Don't give a rat's behind how well the vlog channel does. It only serves your main channel. It turns subscribers into fans.
9) Collaborate, collaborate, collaborate. Contact gaming channels who have about the same number of subscribers as your channel has at that moment and are specializing in the same game genre. As your channel grows, contact bigger and bigger channels. As you're a gaming channel, you can collaborate over the Internet. Fans of gaming channels love YouTubers who challenge each other. It doesn't matter if you win the challenge. All that matters is that you did the collaboration. Be a good sport. Congratulate the winner.
10) Leave your ego off your channel. Always ask your viewers for how you could have done a Let's Play video better. Engage, engage, engage.
11) Ask your viewers for challenges. Do as many as you can. No matter how stupid you might think they are. Every viewer challenge you do, you make that viewer into a fan. Every fan-suggested challenge you do will encourage other viewers to give you more challenges ... which will convert more viewers into fans ... which will encourage more viewers to give you challenges ... which will.... You get the idea.
12) Contact gaming conventions and offer to sit on some of their panels. Tell them about your channel and the game genre that you focus on. Tell them that you will vlog about their convention before you go to it, during it, and afterwards. Needless to say, dump all those vlogs onto your vlog channel. The bigger your channel, the more they will want you BUT don't want until you're big to contact them. Do so now. The worse they can say is "No thanks." No biggie. Reply back thanking them for considering you. Don't argue. Be professional. If you're lucky, they will promote you in their convention booklet. Once accepted, ask if you can put up posters advertising your channel and which panels you'll be participating in at their convention. Put up as many of these posters as they will let you and good taste dictates. If you go there with a friend, have them hand out third-page flyers to all those who attended your panel discussion as they leave. The flyers advertise your channel.
13) Go in and talk to your local gaming stores. Talk to all that you can reasonably commute to. And by "reasonably" I mean as far as you're willing to travel to make your channel a success. Bring your video camera (and lighting, microphone, etc.) with you and ask them if you can interview them for your vlog channel. Flattery will get you everywhere. Later ask if you could put up a poster in their store that advertises your channel to their customers. Keep that relationship alive by doing an occasional Let's Play video with them.