How it works
1. Look
A grid of near-identical color tiles appears. Exactly one is different.
2. Find
Tap the odd tile. Each level shrinks the color difference a little more.
3. Survive
Correct answers add time, mistakes cost double. When the timer runs out, your rank is set.
Difficulty that is actually fair
Most color games make levels harder by feel. This one measures every step in ΔE — the standard metric for how different two colors look to human eyes — and scales it down level by level. When you fail at level 14, it is your eyes, not a random color roll.
How the calibration works →Seven ranks, from Rookie to Oracle
Tap a rank to see what it takes.
Frequently asked questions
Is this a medical color vision test?
No. This is an entertainment game. It exercises color discrimination, but it is not a diagnosis or a medical screening tool — for real concerns about color vision, consult an eye care professional.
How does the difficulty work?
Every level is generated with a calibrated perceptual color difference (ΔE in CIE Lab space). The difference shrinks as you climb, and the grid grows from 3×3 to 7×7 — so difficulty rises fairly instead of randomly.
What is a good score?
Most people clear 8–12 levels on a first run; trained players reach 15–20. Clear 25 and you join the Oracle rank, which very few players ever see.
Is it free? Do I need to download anything?
It is completely free and runs right in your browser — no download, no account, no sign-up. Your best scores are stored on your own device.
What is the highest rank?
Oracle. Ranks run from Rookie through Apprentice, Mole, Hound, Hawk and Eagle Eye up to Oracle — each with its own page explaining what it takes.