I built a decently polished open-source clone of 2048 for iOS over a weekend, and from HN's front page it's obvious many could (and did) do the same for a variety of platforms and languages. It's popular to talk about how ideas are cheap and plentiful, and implementation is what really matters. But maybe Threes is an example where the opposite is true: implementation is straightforward, but the ideas, thought, and polish that goes into making the product truly spectacular are the distinguishing factor.