“The most loved interaction is the unlocking of that stone — when you get granted a new gemstone because you've passed a new milestone. You get to tap to crack the gemstone and that's the most-talked-about interaction. People really remember this and talk about it and it really helps build the brand.”

The gemstone crack interaction cost weeks of engineering — it became the most-loved moment in the app

Schlenker describes Opal's signature reward interaction: users who hit focus milestones receive an opaque gemstone they can tap to crack open, revealing a new unique gemstone of varying colors and shapes. Schlenker is candid that this was expensive to build and hard to justify on a sprint backlog — there were always 50 more urgent things. But the tap-to-crack gemstone became the interaction users describe to friends, the thing they screenshot, and the moment most associated with Opal as a brand. Unreasonably crafted microinteractions compound into differentiation.