These days I suppose a lot of it is about marketing and hype on forums, blogs, social media, youtube etc. There needs to be a lot of links out there to your game and it needs to be featured where it will get views and generate some sort of hype.
also, many indi devs dont realize but, mobile market is very different to even 5 years ago. on mobile now, you are up against games like Fortnight and Candycrush which have captured and, more importantly, retained absolutely massive huge chunks of the mobile player pool. How do you drag players away from those games I dont know.
and on top of that many of the really big players with huge marketing budgets are now devoting massive resources to break the Chinese mobile market and hooking up with large Chinese companies to produce massive mobile titles with very addictive micro-transaction based game-play mechanics. eg Blizzard recent announcement about Diablo.
Im not saying it is impossible, there are a lot of indi developers making a lot of money and the market is ever growing.
But yea, I didnt really answer your question but I suppose my answer is , these days, it is not about just making a good game with a slightly new game-play mechanic but you also need really clever marketing tactics to generate shares and views.