Getting subscribers is always very hard no matter your channels niche and gaming is a very saturated and competitive market, one of the hardest niches. I'm still a small channel but it's going in the right direction. For me it started very slow, it took me about 3 years to reach 1000 subscribers but 1000 - 2000 took me less then a year and now I'm halfway to 3k.
This is kind of what I have learned from the gaming niche:
I started making videos for a huge and very popular game. Thousands if not tens of thousands other channels where making videos about this game since it was so popular. As a new channel every other channel making videos about the game was larger and more popular than mine so my videos just drowned among hundreds of thousands of other videos about the game from more popular channels. In the beginning that was ok, I had no though about growth and I just did the videos to entertain a few friends. But there where no way in hell my channel would grow inside that gaming niche since it was just too popular.
I realized that another much smaller gaming series that I had been playing for years just had a few (compared to the much larger game) content creators crating YouTube content for that game. So I decided to try to make a few videos for that game and I realized that it was much easier for people to find my content for that game compared to the big game I had been creating content for before. But even with this smaller competition as a new channel without barely any subs and just a small amount of views it was still very hard for people to find my videos so I started to look into it a bit more and I realized that most videos other people did for this game was let's plays but barely anyone did guides. So I decided to start making a few tutorials for that game and the result came quickly, since very few people where making tutorials mine showed up high in the search results and the numbers of views I was getting growled quickly. Subscribers didn't grow as fast but much faster than before.
Basically what I did from the beginning where that I created videos for a niche within a niche (nice = the popular game, within a niche = gaming), that don't work for a new small channel, to competitive and nobody finds your videos. Then I started to do videos for a niche, within a niche, within a niche (niche = tutorials, within a niche = smaller game, within a niche = gaming) and that made it possible for people to find my videos.
I still do let's plays every now and then, because I enjoy them, they don't get nowhere near the amount of views as my guides but because of the growth my channel got from the guides my let's play get's more views and are easier to find. Last year I also tried branching out to another newly released smaller game and I used what I learnt, started small with guides and then a few let's plays and it worked pretty good.