Draw lines along the grid edges to divide the grid into rectangles, so that each rectangle contains exactly one clue and is what that clue asks for. What a clue can ask depends on the game mode:
On a touch screen, a tap does what a click does, and a long press what a right-click does (more ways to right-click).
Click and drag from one grid corner to another, or from one square center to another, to draw a rectangle. You can also drag along a grid line to just draw a line at a time, or just click on a single grid edge to draw or erase it.
A drag that starts on a square of a rectangle you have drawn round one clue, by a drag, resizes that rectangle instead. Drag out of it and it grows to take in the square under the pointer; drag within it and the side nearest where you pressed follows the pointer in. Its old sides are taken up, but for those it shares with another rectangle you have drawn, and it stops growing where it would run into one.
While you drag, the status line shows the size of the rectangle. Drawing a rectangle also clears any lines inside it. Right-drag across an area to clear the lines inside it without drawing its outline.
With the keyboard, the arrow keys move a cursor from square to square. Press Enter to start a rectangle at the cursor, move the cursor, and press Enter again to draw it; on a square of a rectangle you have drawn round one clue, the same keys resize it. Use Space in place of Enter to clear the lines inside the area instead. Escape abandons a rectangle you have started.
Each clue has a color of its own. Its square shows it from the start, and a rectangle you draw round it fills with it as soon as you draw it. Its sides are in the clue’s color while it may still grow, the side two such rectangles share among them, and become plain lines once it has the clue’s number of squares. One that no rectangle the clue allows could contain is outlined in red. A rectangle closed by lines drawn one at a time takes its clue’s color once it is a size and shape the clue allows.
A clue drawn in a frame names its rectangle’s shape: a square frame asks for equal sides, a tall one for a rectangle higher than it is wide, and a wide one for one wider than it is high. A square of one cell counts as a square. A clue with no frame allows any shape. A number is how many squares the rectangle has, and a question mark says nothing of it.
Rectangles is Nikoli’s Shikaku. Patches is the puzzle LinkedIn publishes daily under that name.
Hint explains the next rectangle rather than simply drawing it, and says why no other will do. It reads only what is on the board: the clues and the lines you have drawn, so it carries on from wherever you are; if one of your lines is wrong, it asks you to fix the highlighted mistakes first.
A clue’s fits are the rectangles it allows that contain it, stay on the board, take in no other clue and cross none of your lines. A clue with a number allows the rectangles of that size; in Patches, a clue with a shape allows only that shape, and one with a question mark allows every size. These are the ideas the hint teaches, from the plainest up:
An Easy puzzle needs only the first three; a Normal one needs the last two as well, and the hint uses them only where the first three have nothing left.
A rectangle you have drawn round a clue tells the hint that those squares are the clue’s: its fits are the ones that contain it, and no other clue’s may use them. Until it has the clue’s number of squares it may still grow, so its sides are not taken as lines, and it is not a mistake for being too small, only for taking a square the clue’s rectangle does not have. Where the hint finds that one is the whole of its clue’s already, it moves on without a step.
On an Unreasonable board there comes a point where none of these settles a rectangle or a line. The hint then says that nothing further follows by deduction instead of choosing for you. Save your position and try one of the fits of a clue that has only two or three left: if it is wrong, a few forced rectangles later some clue has no fit left, or a square has no rectangle that can cover it. The hint carries on from whatever you draw.
These parameters are available from the ‘Custom type…’ option on the ‘Type’ menu.