There's only one thing that works in mobile games marketing

During the Game Horizon conference on 27 Jun 2012 Natural Motion CEO Torsten Reil told industry peers that mobile games marketing is ineffective.

We learnt the hard way that we really needed to rethink marketing. I don't think it works at all.

Given how many developers have only just learned that you need to know your way around marketing terms and advertise your work, this is a daunting prospect.
Fortunately Mr. Reil also told the audience that judging from his experience when dealing with mobile devices and AppStores the icon and name of the application are immensly important, and;

You can go viral in the old fashioned way on these devices. People will go out to a pub and show your game to their friends if they really like it. Very often it's because of production values and overall graphics. This is where we have a huge opportunity. We always want to wow people.

In other words: Quality is what it's all about.

Source: gamesindustry via Peter Cohen