How to play Reaction Duel
- Each player has a big pad of their own colour. On a phone held upright, Orange's pad is at the bottom and Purple's is at the top. On a wide screen they sit side by side.
- Watch the light in the middle. While it shows three dots, wait.
- When the yellow star appears, tap your pad as fast as you can. The first tap wins the point, and the game shows how fast it was, in milliseconds.
- Tap before the star and you lose the point. That's a false start.
- From the third point on, a blue circle sometimes flashes before the star. It is a decoy: only the star counts.
- The first player to 5 points wins the round.
Controls
| Device | Orange | Purple |
|---|---|---|
| Phone or tablet | Tap the orange pad | Tap the purple pad |
| Mouse | Click your pad | Click your pad |
| Keyboard | A or Space | L or Enter |
Against the computer, any of these keys works for you.
Computer levels
The computer can't see the star any sooner than you can. It reacts after a reaction time of its own, and sometimes it falls for the decoy too.
| Level | Typical reaction time | Fooled by the decoy |
|---|---|---|
| Easy | About 470 milliseconds | Quite often |
| Medium | About 360 milliseconds | Sometimes |
| Hard | About 285 milliseconds | Now and then |
| Expert | About 230 milliseconds | Hardly ever |
Most people react to something they see in about a quarter of a second (250 milliseconds), so Hard and Expert are a real test.
Tips to win
- Watch the light, not your finger. Keep your eyes on the middle and let your finger rest on the pad, ready to press.
- Don't guess. The wait before the star is random, so trying to predict it only leads to false starts.
- Ignore the blue circle. Train yourself to react to the star's shape and colour, not to any change.
- Stay relaxed. A tense hand is slower. Take a breath between points.
- Keep the phone steady. Lay it flat on a table between you, so neither player has to hold it while tapping.
About reaction games
Scientists have measured reaction times for well over a hundred years, and "who's fastest?" games are a party favourite everywhere. A reaction time is the gap between seeing a signal and pressing a button, and it changes with tiredness, focus and practice. Reaction Duel turns that into a head-to-head contest, with decoys to keep both players honest.
Questions
What is a good reaction time?
Many people tap in about 250 milliseconds. Under 200 milliseconds is very fast. The game shows the winner's time after every point, so you can watch yourself improve.
Why did I lose the point when I tapped?
You probably tapped before the star appeared, or tapped at the blue decoy. Both count as a false start, and the point goes to your rival.
Can two people play on one phone?
Yes. Choose 2 Players, hold the phone between you and use your own pad. Both players can tap at the same time.
Is Reaction Duel free?
Yes. It's free in your browser, with no download, no sign-up and no ads during a match.
Updated 2 November 2026