Color Reflex

How this works

A score here is a score in this game, on this device, on this screen, today. Perception varies by display and lighting, a browser's own timing varies by device, and this is not a medical eye test or a clinical measurement of reaction time.

Nine colours, one answer. The board changes every time you get it right, and one wrong tap ends the run.

A board is nine cells and one target. The target is one shade of one hue; some of the other cells are the other shades of that same hue — same colour, different lightness — and the rest are drawn from other hues and other lightnesses entirely. Finding it is a search, and what makes it a harder search is not the clock: the closer the wrong shades are allowed to sit, and the more of the nine cells that are shades of the target's own hue, the more of the board has to be compared against the target rather than glanced at. Levels 1 to 5 do the first half of that, levels 6 to 10 do the second, and the clock tightens throughout.

Every colour on the board comes from a table of 108 measured values, built in OKLCH at 80% of the greatest chroma sRGB can hold at each lightness. The table's distances are proved rather than assumed: adjacent shades of one hue are at least ΔE OK 0.0187 apart and at least six steps of 8-bit RGB in some channel, two shades ≥ 0.0401, five shades ≥ 0.1046, and a cell from another hue at the same lightness ≥ 0.0721. That means the nearest wrong cell on the easiest board is at least a tenth of a full difference away, and on the hardest it is never closer than this product's own definition of two colours being the same — which is what makes a lost run a matter of speed rather than a matter of the board being a trick.

The clock is the part worth being precise about, because a millisecond is the game's own unit. It starts at the moment the board is painted — the renderer waits for the frame that put it on screen and reports it — and stops at the press, taken from the browser's own event timestamp rather than from when this page got around to handling it. A press that arrives before the board has painted is refused, which is what stops one tap from being counted twice, and a run that is left in a background tab keeps its clock running: the deadline is a moment, not a countdown of frames.

A cell is worth 50 points plus 10 for every level of difficulty, plus up to 100 more for answering quickly — scored against that level's own response window, so a fast answer on an easy board is not rewarded the way a fast answer on a hard one is. Each consecutive correct answer multiplies the lot by another tenth, up to 1.5×. The fastest and average times on the result screen are your own, measured the same way, so the number to beat is your own.

Playable with a keyboard, since every cell is a button. The target's hex value is printed beside it, and the no-time-limit option writes every hex into one polite live region — which turns the game into a reading task for anyone who cannot see the board, at the cost of a score that earns no speed bonus at all. The search is carried by lightness as much as by hue, so it does not depend on telling two hues apart; it does still require seeing the board, and that is a limit this game cannot talk its way out of.

Nothing here is uploaded and there is no account. Your best score is one whole number kept in this browser, with no timestamp, no identifier and no history beside it, and it is the fourth and last record this product writes to your device — the other three are the working palette, your light or dark choice, and the color memory game 's best. Clearing this site's data removes all four. If you would rather hunt for a difference than search for a match, there is the Color Challenge , and the contrast checker and color converter are the tools the same colour engine runs.

What a reaction time test measures, and what this one does

A simple reaction time test shows one thing and waits for one expected reply: the screen changes colour and you click. Nothing has to be found and nothing has to be chosen, so the interval it reports is mostly the loop from eye to hand. Published averages for adults sit close to a quarter of a second, and Human Benchmark publishes a median of about 273 ms from the results it has collected.

This game is not that. The clock starts when the board is painted and stops at your press, and finding the matching cell among nine happens inside the interval — so the number includes a search. A good time here is therefore larger than a good time on a reaction test, and that is not a defect of the measurement: it is the difference psychology has always drawn between a simple reaction and a choice one, where the response depends on working out what the stimulus was. Summaries of the classic literature put simple visual reactions near 220 ms and recognition reactions near 384 ms, and the gap between those two figures is exactly the search this game is about.

So the fastest and average times on the result screen are yours and only yours, and the fair comparison is against your own last run on the same screen. A time that would be a poor reaction time is often a perfectly good search time.

What changes your time

Sleep and alertness first — the difference between a well-rested run and a run at the end of a long day is larger than any of the tricks below. Then attention: a second screen, a conversation or a notification costs more than the second it appears to take. Age moves visual reaction time slowly upward, and no amount of practice removes that. Then the hardware: a mouse and a finger are not the same instrument, a display running at 60 Hz adds a frame or two of its own to whatever the panel does, and a bright room at low screen brightness makes every subtle shade harder to separate.

What that leaves is strategy, which is the part worth practising. Look at the target before the board rather than after it: the search is faster when you know what you are searching for. Scan for the strongest edge or the lightest cell instead of reading all nine in turn. On a phone, keep your thumb resting over the board so the press costs no travel. And if a level keeps ending your run, play it with the time limit switched off until the palette stops being a surprise — the clock only pays for speed, it does not gate anything.