Overview

Besides the puzzles Nuleen generates, you can play puzzles from other sources, such as a newspaper or another app, and make your own. Both happen on the Enter puzzle screen, which you open from the "…" menu on the main screen.

Working on a puzzle there has two stages:

1. Entering clues until the puzzle has exactly one solution.
2. Fine-tuning: removing clues while the solution stays unique, which makes the puzzle harder.

Whatever you enter is kept for each grid size, so you can close the screen or switch sizes without losing your work.

Entering a puzzle

Choose the size (6×6, 8×8 or 10×10) at the top. Then use any of these ways:

Tapping the cells. Each tap changes a cell from empty to 0, to 1, and back to empty. A long press puts a 1 in a cell directly. This is the way to copy a puzzle from a newspaper.

Pasting text. Copy a puzzle in text form and tap the paste button under the board. A puzzle shared as text from Nuleen works this way, and so does text from elsewhere in this form: one line per row, with 0 and 1 for the clues and a dot for an empty cell.

Nuleen 6×6
Name: Newspaper, 17 October
.0.00.
0..0.1
....1.
1..1..
.1..0.
.0....

This example has one solution, so you can try it. The first line and the Name: line are optional. A name is suggested when you add the puzzle to your favorites. Empty cells may also be written as _, - or x.

Pasting a screenshot. Take a screenshot of a puzzle, for example in a newspaper's app, copy it, and tap the paste button. Nuleen reads the digits from the picture.

• The whole board, with its thick border, must be visible.
• The board must not be too small in the picture: use a screenshot rather than a small part of a page.
• If the picture holds two puzzles, you choose which one to use.
• Cells the reader was unsure about are marked in blue. Check them against the original before going on.

Stage 1: one solution

While you enter clues, Nuleen checks them in the background and tells you where things stand, under the board:

• The clues break a rule: the cells involved are marked in orange. Often a mistyped clue.
• No solution fits these clues: one of the clues is probably wrong.
• More than one solution: more clues are needed. Switch on Mark differing cells (the first button under the board) to see where the solutions differ: a clue in one of the blue cells rules some of them out.
• Unique solution: the puzzle is complete. Nuleen now shows how many clues it has, which technique it needs, which star level it is comparable to, and the size of its symmetry family.

Once the solution is unique, more buttons appear under the board:

• Show solution (the eye): shows the solution; tap again for the clues.
• Add to favorites: keeps the puzzle in your favorites, with a name.
• Play: starts the puzzle on the main screen.
• Remove clues: the switch at the right edge, for stage 2.

Stage 2: removing clues

With Remove clues switched on, Nuleen marks in blue every clue that could be removed with the solution staying unique. Tap a marked clue to remove it. The marks are then worked out again, because removing one clue changes which others can go. Other cells don't react while the switch is on.

Each removal makes the puzzle harder, and the estimated level follows. When no clue is marked any more, Nuleen says Every clue is needed: the puzzle is as sparse as it can be along the way you took. A different order of removals can lead to a different end result.

Making your own puzzle from scratch

The two stages also work for a puzzle of your own:

• Starting from an empty grid: enter clues, with Mark differing cells switched on, until the solution is unique. Then remove clues in stage 2.
• Starting from a complete grid: fill in a whole valid grid, or copy a solution. It is unique by definition, so you can go straight to stage 2 and remove clues until every remaining clue is needed.

Keep the result as a favorite, or play it straight away. To share it, play it and use Share / Save in the "…" menu, or share it from its favorite.

Scores

The best results of Speed solving games are kept for each grid size and level, the best ten of each. Best means fewest hints, then fastest; a result with hints shows their number in square brackets, as in [2] 4 min 12 sec. Open them with Scores in the "…" menu, and tap a score to see its puzzle, with the clues or the solution. Play again replays it.

• A puzzle counts as the same puzzle in every orientation, so replaying it after turning or mirroring it improves the same score instead of adding a new one.
• A solve with hints never pushes out a solve without hints. Each hint also adds a little time to the clock.
• Zen games, solves with more hints than the limit, and solves where the solution was shown during the game are not recorded. See Playing a puzzle.
• Puzzles entered on the Enter puzzle screen have no star level, so they stay out of the scores. Their best result is kept with their favorite.
• To clear scores, long press the Scores title: you can clear those of one size and level, or all of them.

Favorites

Favorites keep puzzles you want to play again, also after they have dropped out of the scores. Add a puzzle from Share / Save in the "…" menu, from a score's detail, or from the Enter puzzle screen. Open them with Favorites in the "…" menu.

• Each favorite has a name, an optional note and its own best result, chosen the same way as in the scores: fewest hints, then fastest. Tap it to see its puzzle, its analysis and these details, and to play it.
• Search by name or note at the top of the list. The "…" menu sorts the list (newest first, by level or by name) and lets you select several favorites, to export them as text or delete them.
• Swipe a favorite to the left, or press it, to delete it.