I used to play Minecraft from time to time and I always knew it is going to go big. I had an idea of an app with various Minecraft-like frames that you could use for your photos. I knew it could be successful, because people loved everything Minecraft-related. This app featured all the items present in the Minecraft at the time, you could select any item you wanted and take a picture with this item in a frame. Photo would be then rendered and merged with the frame and saved to your gallery. Even though there were not many downloads in the beginning, somehow the app "exploded" after few weeks and got around 2.3 million downloads before my account got suspended. It was also a first app popping up for keyword "Minecraft" for few weeks. It was my main source of income and most maintained app for few months. Great experience.