Submit Articles, Press Releases, Social Bookmarking, Blog Commenting and so-on. All these will help, but the key here is Quality Content and Quality Backlinks.
Try to not to put everything in one effort balancing between article submission,, directory submission, social book marking, social media networks, video promotion and other basics
Can anybody explain how to social bookmark, how to submit to directories and how to promote. I need specific info here! lol
You really need to start with some lower hanging fruit. There are 188 million competing pages for "flash games". If you haven't already, try a copy of Market Samurai to do some more keyword research. As far as the amount of times your keyword needs to appear, it will be a good idea to make a page for each keyword and focus on that keyword. I know your site is a collection of games, but you maybe you can add some pages specific to each keyword and build links to those pages.
#1 - keywords research (if you want to rank on first google page very first, try to find keywords with maximum 10,000 SERP and some decent searches). #2 - find a domain name identical with your main keywords (.com, .net, .org). #3 - make your site for your 10-20 or more keywords - use great unique articles (keyword enriches) and don't forget about onpage seo. #4 - promote your site