My recommendation would be to focus on improving your youtube marketing first. Your SEO is not great, only "letherplay" seems to rank your video. Your description are super short as well, no links to other video's, really not much for the search engine to chew on so people can find you. Try to read some SEO guides on the forum or on google, they contain a lot of information.
Also, for a lets play channel you don't post frequently enough in my opinion and the games you chose are very competitive to be in. There's a ton of channels out there with the same games but with much more authority than you so the only way you can gain some viewers is SEO.
I'm sure you have some favorite youtubers who you consider great, watch what they do, how frequent they post, etc.