Arrange the shuffled chips into a smooth colour gradient.
Ready when you are
Hue Sort is a colour-arrangement game inspired by the Farnsworth-Munsell 100 hue test, a tool eye clinics have used since the 1940s to grade how finely someone can tell nearby colours apart. Each round hands you a row of chips that belong on a smooth gradient running from one end to the other. The two end chips are locked as reference points; everything between them arrives shuffled, and you rebuild the sequence.
Sorting happens by swapping. Tap one chip, then tap a second, and the two trade places. There is no drag step and no penalty for experimenting, so you can move a chip, step back to judge the row, and move it again. When the transition from the left reference to the right one reads as even, with no chip that looks lighter, greener, or more saturated than the one after it, submit the round.
The game picks two anchor colours far enough apart in hue to be orderable but close enough that the in-between steps stay subtle, then fills the row by blending evenly between them across hue, saturation, and brightness. Round one gives you four chips, and each following round adds one more, up to eight in round five. Fewer chips mean bigger jumps between neighbours; more chips squeeze those jumps down until adjacent tiles differ by a hair. The two anchors never move, so you always have a fixed start and end to reason from.
Anchor your eye to the two locked ends first and decide which direction the gradient travels — getting warmer, darker, or less saturated. Then place the chips that are obviously nearest each end, since those are the easiest calls, and leave the murky middle for last. When two neighbours look almost identical, stop staring at them directly; glance at the chip on either side and ask which order makes the three-in-a-row change in one steady direction. Squinting to blur the fine detail can make an out-of-place tile pop out as a bump in the gradient. If you get stuck, our guide to training your eye for colour covers the same comparison habits in more depth.
Ordering a gradient is a test of hue discrimination: how small a difference in colour you can reliably detect. That skill sits behind a lot of practical work, from matching paint and grading photos to reading a heat map correctly. Roughly one in twelve men and one in two hundred women have some form of colour-vision deficiency, which usually shows up first as trouble ordering the closely spaced chips, not as confusing bold primaries. If you are curious where your own perception lands, the Ishihara-style dot mode probes red-green sensitivity from a different angle, and how many colours you can see puts some numbers to it.
The usual slip is sorting by lightness alone. A row can look tidy from dark to light while the hue underneath zigzags, so check that the colour family shifts smoothly as well. Another is trusting a first glance on the tightest pairs; give the middle chips a second pass once the ends are settled, because a single swapped pair drags down every position it touches. And do not over-swap — once the row reads clean end to end, more shuffling tends to reintroduce errors rather than remove them.
Hue Sort grades every slot, not just whether the row is perfect. After you submit, the colour sitting in each position is compared against the colour that belongs there, and the perceptual gap is measured with CIEDE2000 — the same distance formula explained in our CIEDE2000 primer. Those per-slot results are averaged into a single round score from 0 to 10, so a row with more chips is not automatically harder to score well on. Because the metric is perceptual, a chip nudged one place out of line barely dents your total, while a chip parked at the wrong end drops two positions at once and hurts. The two locked anchors always land correctly, which sets a small floor under every round. Prefer scoring against a fixed swatch instead of a whole row? The Gradient guess mode and the core guess-the-colour game use the same distance measure on a single target.
