Without trying to sound too harsh, and apologies to the developer it does, this seems to be a case of "Launch mediocre game with no marketing to Google Play and make no money." I'm not really sure what he was expecting.

I suggest:

1. Use this as a learning experience for how the Google Play store works.

2. Find an artist to work with (this looks like programmer art).

3. Develop a game that innovates on the genre you wish to work in.

4. Try again, and keep trying.

It's not like launching games on the iPhone app store is any easier. Especially since most professional studio games are moving to a free + in-app-purchase model, which is hard to compete with if you are charging for your app and don't have a full team working on it.

I think there are hundreds of thousands of apps in the market (not sure about the exact numbers). So naturally there is some competition. Build it and they will come probably won't work.

I miss some notes on marketing in the article.

I'd like to know as well, but from what I've seen just watching the top apps is that the people who make the most money have in-app purchases. Part of it probably also has to do with marketing, I don't know if the author of this article did a lot of advertising or promotion, but it is important.