Puzzle games that work offline on iPad

On a train with no signal, a player holds an iPad that has 20% battery left. About ten minutes pass before the next stop, which is enough time for a 4x4 board. When the player opens the puzzle app, a spinning circle appears where the level should be.

Many puzzle apps expect the player to be online. Some apps download each level as it opens, others require signing in to an account first, and others sync progress before showing anything. Players on a home network rarely notice any of this. The board never loads for players on a train, a plane or a platform with weak reception.

Players who check ahead of a trip can avoid this problem. A test at home with wifi off takes about a minute and shows which features still work. Running the same test at the gate, while the boarding line moves, leaves no time to find another game or charge the battery.

What to check in a puzzle app before a trip

Three checks show whether an app will work without a connection, and each one can be tested in a few minutes at home.

The first question is whether the levels are stored on the device. Some apps store every board inside the app after installation, but others fetch each board from a server whenever it is opened. Players can usually tell from what happens after the first tap: a stored level shows up immediately, while a fetched level leaves a blank grid or a spinning circle.

The second question is whether the app requires a sign-in or a sync before a level can begin. A screen that asks for an account or reports that progress is updating is a warning sign for anyone offline.

The third question is whether the app displays a clear message when the connection drops. A useful message explains what is unavailable and lets the player continue with everything else. A silent freeze forces the player to guess what went wrong.

For a test of all three, switch on airplane mode, fully close the app, reopen it, and play one complete level. A slow load is easy to spot: the grid arrives in pieces, the timer starts before the numbers appear, or the screen stays blank for several seconds. Any of these at home will be worse on a train.

Puzzle types that need no connection on a 9×9 board

On a 4x4 grid of sixteen cells, a solver can check every rule by eye, since each row, column and box holds each number once. A 6x6 grid works the same way with larger boxes. The board does not rely on a server, so a player needs only the board and the rules. A paper grid works as well as a screen, and a level stored inside an app works the same way once the app is installed.

Logic grids on a 9×9 board follow the same idea at a larger size. The solver scans rows, columns and boxes for a cell that has only one possible number, then writes it in. Players often pencil small candidate numbers into the corners of cells. This works on paper and in any app that keeps its levels on the device. The format has been in print since April 1984, when a Japanese magazine first published it, and it was built for pencil and paper long before any connection existed.

Daily puzzles are different. Many apps deliver a new board each morning, and the board may need to download before it opens. A player who plans to play offline can test this at home by opening the daily puzzle with airplane mode turned on. If the daily board shows a blank grid or an error, a stored level or a paper grid makes the safer choice for the trip.

Planning an offline session on an iPad

A 4x4 board fits a wait of about ten minutes, such as the stretch between two stops. A sixteen-cell board leaves little to work through, and most players finish with a minute or two left. A 6x6 board fits a longer leg of perhaps thirty minutes, since its larger boxes and extra numbers add more rows and columns to check.

On a slip of paper or in a notes app, a player can write the board size and the time limit before leaving home. Then the choice is already made when the train starts moving.

A paper copy of the board protects the work if the battery runs low. At around 20%, the player copies the current grid onto paper, filling in the numbers placed so far. Pencil candidates can go in the corners of cells. Once the iPad shuts off, the player can keep solving on the page and enter the remaining numbers later.

One routine covers a session:

• Pick the board size that fits the time available.
• Set a timer for that length.
• Stop when the timer ends, even if the board is unfinished.

The paper copy then holds the unfinished board till the next session.

NumFall is made by the publisher of this site. Any health or brain-training points here are general information, not medical advice.