Echo: N-Back Math

You just spent an hour scrolling and remember none of it.

That's not your fault. Every other app is built to fragment your attention and hand it back in small, restless pieces. Echo does the opposite.

A number appears. A few seconds later, another. Add the new one to the number you saw a few steps back — and type it before it slips away. No feed. No autoplay. No bottomless content. Just one number at a time, and the quiet pressure of holding something in your head.

It's deceptively hard, and that's the point. The more it pulls on your short-term memory, the more it asks for the one thing the feed never does: your full attention.

— Three difficulties: look back 1, 2, or 3 steps
— Path mode: levels that ramp from gentle to merciless
— Hands-free Voice mode: it reads each number and listens for your answer, in English or Mandarin — eyes off, screen down
— A signature echo tone, synthesized live, on a pitch-black canvas
— Streak and best score — no leaderboard to perform for
— Fully offline. No account. No ads in your face.

Echo Pro (one-time, optional): every stage's 2-back and 3-back levels, plus unlimited Voice mode. Buy once. No subscription.

Put the feed down for ninety seconds. See how long your streak lasts.