I don't know why everyone thinks that getting an app featured by Apple is some sort of huge conspiracy. If an app is of high quality and has some traction, it's not absurd for it to gain positive attention from Apple.
In the case of Halftone, the quality of the app is excellent and has significant usage. There are 1100+ reviews that average to 4.5 stars. These numbers would be considered fantastic by any developer's standards.