Hueman

A grid of tiles in one colour, except one of them is a fraction of a shade off. Find it before the bar empties. Clear a level and the next one squeezes the difference, adds tiles and shaves the clock, so the game is a ladder that keeps getting steeper until your eyes give out. Three lives, and the level you died on is your score.

1. Hit start. The clock is already running on level one, at around ten seconds.
2. Scan the grid for the tile that is not quite the same shade as its neighbours, and tap it.
3. Clear it and you move up. The grid steps from four tiles to nine, sixteen, twenty five and on to a thirty six tile board, while the timer drops by a fraction of a second each level.
4. A wrong tap or a timeout costs a life and drops you back onto the same level to try again.
5. When the third life goes, the run ends and your final level is the score you share.

Hueman is the shortest daily on this list to explain and the hardest to argue with: one tile is different, find it. What makes it hold up is the ramp. The colour gap narrows, the grid grows and the clock shrinks on every single level, so the run always ends with you failing at the exact point your eyes stop resolving the difference, which is a genuinely interesting number to get back. It takes about two minutes, needs no account, and the end card breaks down where each of your three lives went. The developers are also clear about what it is not: they state plainly that it is a game rather than a colour vision test, and that the shade differences include brightness shifts so it stays playable for most people with colour vision deficiency. It is free and ad-supported, with paid credits that buy extra ranked attempts on a separate board and never make the odd tile easier to see.

Brutally simple: right or wrong, immediately. Clear the tile and the next grid appears; miss it and one of the three dots at the top goes dark. There is no warmer or colder, no second look, no partial credit. The end card does the analysis for you instead, showing the number of levels cleared, how long the run lasted, a percentile for the day and, usefully, which level each of your three lives was lost on.

Daily puzzle

The ranked run. One puzzle a day, identical for everyone, and only your first attempt counts on the Daily board. Once it is filed it cannot be changed.

Practice round

One free unranked go a day, built from random colours rather than the day's puzzle. It touches nothing: not your streak, not your stats, neither leaderboard.

Unlimited

A second board that ranks your best run of the day rather than your first. Every free player is on it automatically with their single run; paid credits buy extra attempts at the same puzzle, and optional handicaps like an extra life or a slower clock, but never a bigger colour difference.

Archive

Every previous daily, numbered and dated, playable from a single index.

• Do not stare at one tile. The difference is a comparison, not a property, so sweeping your eyes across the grid catches it far faster than inspecting candidates one by one.
• Use the edges and corners. On the bigger boards a tile with only two or three neighbours is easier to judge than one surrounded on all sides, and the odd tile is as likely to be there as anywhere.
• Spend your practice round before the real one on days when you feel rusty. It costs nothing, it is unranked by design, and it gets your eyes calibrated before the run that goes on the board.
• Screen brightness and glare are part of the game whether you like it or not. Later levels turn on differences small enough that a dimmed phone in sunlight will lose you a life that a decent screen would not have.
• When a life goes you restart the same level, not the run, so a death is a retry rather than a disaster. Panic-tapping to beat the clock is what actually ends runs early.