Side Step

A card appears on the left or the right, and it says LEFT or RIGHT. Press what it says — where it appeared does not matter. Sometimes the two agree and it is easy; sometimes they conflict and you will feel yourself hesitate. At the end the game shows you exactly how much that hesitation cost, in your own numbers.

It runs entirely on your device: 0 network requests, works offline. No ads, no account, nothing to buy, and no betting, money or prizes of any kind.

1. Focus the board — click it, or press Tab until it is focused.
2. Answer with the arrow keys — press ← or → for what the word says. The two buttons below do the same thing for touch.
3. Beat the fuse. The bar under the card is your time for this round; letting it empty costs a life, just like a wrong answer.
4. Keep going. Every correct answer shortens the next fuse slightly. Three lives, and the round is over.
5. Read the result. It compares your average when the cues matched against your average when they conflicted.

Why is it harder to respond when a cue conflicts with its position?

Because you process both cues whether you want to or not. Seeing something on the left prepares a left-hand response before you have finished reading the word, so when the word says "right" you have to suppress a response that is already under way — and suppression takes time. Psychologists call this the Simon effect, and it is remarkably robust: it shows up in almost everyone, it does not go away with practice, and knowing about it does not make it stop. What does help is committing to one rule before the card appears rather than deciding after it, which is the habit this game trains.

What are the two numbers at the end?

Your average response time on trials where the word and the side agreed, and on trials where they conflicted. The gap between them is your Simon effect. A gap is normal and expected; no gap at all usually means the round was too short to measure, which is why the game says so rather than pretending the number means something.

Is this a real psychology test?

It is the same task, but it is a game, not an assessment. Real measurement uses many more trials, a controlled environment and no scoring pressure. Treat the number as something interesting about your afternoon, not as a result about you.

Does it use colour to make it harder?

No, deliberately. The better-known version of this effect prints a colour word in a conflicting ink, which would make the game unplayable for anyone who cannot distinguish those colours. Position and text produce the same interference and everyone can perceive both.

Does it work offline?

Yes. Once the page has loaded once, the whole game is on your device — the trials are generated locally from a seed. There is no server involved in play at any point.

Is there any money, betting or in-app purchase in this?

None, and there never will be. No currency, nothing to buy, no lives to refill for a fee, no wager of any kind.

Can I play it with a keyboard or a screen reader?

Both. The arrow keys are the primary control, and the live region announces which side the card is on and what it says, so the conflict is fully audible. The fuse is a labelled progress bar rather than a colour change.

Three lives, a fuse that starts at 1.5 seconds and shortens with every correct answer down to a floor of 0.6 seconds, and a small random variation on each round's time — without that variation you would answer on the rhythm instead of on the card, which would quietly stop measuring reaction at all.

Sequence Echo is the other game here that runs on attention rather than reasoning — it asks you to hold a growing pattern rather than to resolve a conflicting one.

Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.