Crux is a quiet game. It's designed to be played in waiting rooms, on commutes, in the fifteen minutes before sleep. The last thing it should do is demand your ears the way it demands your attention.
And yet, sound is one of the most consistent things players mention in reviews. Not its presence — its quality. "The sounds feel right." "I didn't realise the sound was doing anything until I turned it off." That's what we were going for.
The 80-cue problem
Crux has 80 distinct audio cues. Every interaction — tapping a cell, completing a row, triggering a wrong answer, completing a level — has its own sound. That's more than most mobile games this size.
Tom, our sound designer, started with a guiding principle: every sound should communicate information, not just confirm input. A tap that places a correct value should sound different from one that places a value you'll need to revise. The sound is telling you something before you consciously know it yourself.
Making silence feel like progress
The most counterintuitive decision: the "thinking" state — when you've placed all your current guesses and are working through the logic — has almost no sound at all. Occasional, very quiet ambient tones. Nothing that acknowledges what you're doing.
This was deliberate. The silence creates pressure. It's a container for your thinking. When you finally tap the cell that unlocks the next section, the sound that follows carries all the weight of that silence. It's satisfying in a way that constant audio feedback never could be.
The test we use
We play every level with eyes closed, listening to just the audio. If we can follow what's happening — if the sounds alone tell a coherent story of progress, error, and resolution — the sound design passes. If we feel lost, something needs changing.