Choose carefully the niche you choose, but also stand out in the content you offer.
Propose some real added value to your players, be different.
Brand your website, just do not choose a keyword rich domain (although main keyword good to be in your domain). Brands tend to be trusted more.
Engage your visitors into a conversation (blog, newsletter) and keep them going back to your site.
SEO is not the only way to bring traffic to your site, think outside the box.
And be patient.