The Blockheads is an extremely popular (and profitable) game. David Frampton does a great Post Mortem write up of what went right and wrong:
The Blockheads is an exploration/mining/crafting massive world sandbox game released for iOS in January 2013 and only just launched for Android. To date it has had over 7 million downloads on iOS, and has a passionate and growing fan-base, rarely dipping below 100,000 daily active users since its launch 9 months ago. The Blockheads was entirely made by one guy - me, over the course of about a year, and since version 1.0 Ive released 4 major updates. Its an ever-evolving game, and the potential additions are limitless. Perhaps in part due to this constant evolution, I havent felt I could write a postmortem until now. It still feels a long way from "complete", but I think now with the release of the 1.4 update it finally no longer feels "incomplete". So its time to share some of the story of its development, and where I feel I went right and wrong with The Blockheads.
via Gamasutra: David Framptons Blog - Postmortem: The Blockheads.