That is the whole difficulty of Color Sense Test: one tile is shifted by twenty-five values per channel, and you have twenty seconds to keep finding it. The scope plots both shades at once. They land on top of each other.
Different mode. Every cell is one shade but one, off by 25 of 255 on each channel.
The monitor above is the whole game, running in this page. No download, no sign-up, no account: every tile carries one shade, one does not, and you have twenty seconds to find it. It is the same board the phone app runs.
Two modes, two ways to be wrong. Different mode is the find-the-odd-color grid: one tile is off by 25 of 255 on each channel, in a direction nothing marks. Bar mode puts the target on the reference bars and asks you to match that exact value off them. Slower work, so it grades a few levels lower.
The shift never changes. The board does: 4 tiles, then 9, 16, 25 and 36 at levels 5, 10, 18 and 30, on a clock that starts on your first correct tile and never resets. A wrong tap costs you nothing but a shake. Your score is levels cleared.
The app returns a verdict the instant the clock stops. Its own words, rung for rung.
Rungs shown for Different mode. Bar mode grades the same lines a few levels lower.
The app is the same game plus what a run is worth keeping for: a global leaderboard per mode, a username to climb under, your own colors on the chrome, and a haptic answer on every cell you touch.
Starting with the one that matters most: no, this does not measure your eyesight.