Gradientle

Twenty colour tiles in a five by four grid, scrambled, to be dragged back into a gradient. What makes it more than sorting is that the blend runs in two directions at once, across the rows and down the columns, so every tile has to be right on both axes at the same time. The four corners are fixed and never move, which is what stops the whole thing from being guesswork.

1. Drag a tile onto another to swap the two.
2. Navigate by the corners. They are locked in place, so they define both axes of the blend and every other tile is an interpolation between them.
3. Tap Hint if you are stuck, or Give Up and take tomorrow's puzzle instead.

Sorting colours along a line is a familiar exercise. Gradientle makes the field two-dimensional, and that changes the whole task: a tile can be perfectly placed by hue and still be in the wrong row, and you cannot fix one axis without disturbing the other. Locking the corners is the clever bit, turning what could be a fiddle into a solvable system where the edges are deducible and the interior follows. There is no attempt limit and no losing state, just a grid that either flows or does not, which makes it one of the calmer things on the daily circuit.

There is no colour code and no attempt counter, because the grid itself is the feedback. You are looking for banding, the little jolt where two neighbours do not belong next to each other. The only external help is the hint, which the rules describe simply as highlighting the correct tiles.

Core play

A single default puzzle: a five-by-four grid of twenty colour tiles with the four corner tiles fixed. Tiles are dragged onto one another to swap them as you restore the two-axis gradient (across rows and down columns). The interface offers a Hint that highlights the correct tiles and a Give Up button that moves you on to the next day's puzzle.

• Build the edges before the middle. Each edge is a straight blend between two fixed corners, so it is the part of the grid you can solve with certainty, and it boxes in everything inside.
• Unfocus your eyes. Banding in a gradient shows up far better out of focus than it does when you are comparing two tiles nose to screen.