On top of ALL the comments here, which all have very valid points - even if you had a brand-new, innovative game concept, it's still damn hard to get traction and visibility in the app store(s). Nobody knows why this game is so good or that he needs to have it, and for some of those games, it's really a shame. The situation is comparable to web sites a few years ago. There's basically the SEO way - sideline promotion, forums, reviews, people skills etc. and there's the SEM way. If you invest enough to push your way up in the store through advertising (Trademob, the company that I'm working for, estimates around 10-100k, depending on category and target market), you'll eventually be paid back through the resulting organic installations coming from the visibility once you get into the top charts. TL;DR: In 2013, even for killer apps, there's no way to the top except through the hardship of promotion on all possible channels. Viral campaigns, PR, spreading the word, posting, blogging, and often pure money investment as well.

Sorry, pal!