Best Sudoku App for Your Commute: One Thumb, Patchy Signal

On a train or bus you want three things: a board you can work with one thumb while holding a rail, nothing that pops up between stops, and puzzles that keep going in a tunnel. Sudoku Royale covers the first two well: the number bar and Notes toggle sit under the board at the bottom of the screen, there are no ads, and a number can be armed once and placed with single taps. It covers the third only in part: Practice and Journey work offline, but the Daily Challenge, Dojo and hints need signal. If your route is mostly underground, nerByte Sudoku and Sudoku Master make stronger offline promises.

The App Store facts

From each app's US App Store listing, checked October 26, 2026. Prices and paid items change, so check the listing before you buy.

Commute features side by side

For the other apps, the cells repeat what their own App Store listing says. "Not stated" means the listing is silent, not that the feature is missing.

Playing with one thumb

Standing on a crowded train, your thumb can reach the bottom half of the screen comfortably and the top corners barely. Sudoku Royale puts everything you press repeatedly in that bottom half: the nine number keys and the Notes switch sit below the grid, and the board is the only thing above them.

The input method matters as much as the layout. Tapping a cell and then choosing from a pop-up is two touches per number, spread over the whole board. Number-first play is easier one-handed: tap a key once to arm it, then tap each cell where that digit belongs. Holding a key and swiping along the bar lights up each digit's cells in turn, which is a quick way to scan the board without reaching up. And slide-to-select lets you drag across the grid instead of aiming at small cells while the carriage moves. The number-first versus cell-first guide compares the two styles.

What Sudoku Royale lacks for a lurching bus is undo. Every number is checked as you place it and a wrong one is rejected, so a bump never leaves an error on the board, but there is no button to take back a note you dropped in the wrong cell. Notes are written by hand with the Notes switch, and they clear from the row, column and box when you place a number.

Between stops: interruptions and sound

• No pop-ups. Sudoku Royale has no ads, so nothing appears between puzzles while you are watching for your stop.
• Getting off mid-puzzle. A Practice puzzle you leave is saved and picks up where you stopped on the way home.
• Quiet carriage. Music and sound effects have separate switches in Settings. Haptics have no in-app switch, so the phone will still buzz on some taps.
• Night ride home. The app follows the system theme or can be set to Dark.

Signal: what keeps working in a tunnel

The offline guide goes through flights and long trips. A commute is different: signal comes and goes every few minutes, so what matters is which modes you can count on between stations.

• Safe underground: Practice, using the puzzles already downloaded for your level, and Journey levels once the map has loaded.
• Play above ground: the Daily Challenge, the Dojo drills, hints and Belts all need a connection. Start the Daily on the platform or at home, not in the tunnel.
• Riding with a friend: Play Nearby runs a game over Bluetooth between two phones, with no internet needed. It is an optional extra.

Where another app is the better pick

• You hold the phone sideways or play left-handed. Sudoku Royale is portrait only on iPhone and has no left-handed mode. Brainium's listing offers landscape with a right- or left-handed option, and nerByte supports both orientations.
• Your commute is mostly underground. nerByte Sudoku says it is "offline playable without restrictions", and Sudoku Master and OAKEVER's app both name commuting alongside full offline play.
• You want undo for a shaky ride. Sudoku by Mind The Frog lists undo and redo, plus big buttons.
• You want auto pencil marks. Typing every note with one thumb is slow. Brainium and Mind The Frog list automatic notes; Sudoku Royale does not have them. See the best apps for notes.
• You commute with an Android phone. Sudoku Royale is iPhone and iPad only.

Our pick

For a commute with patchy signal and one free hand, Sudoku Royale is a good fit if you play in portrait and want no interruptions: open a Practice puzzle before you go underground and save the Daily for the platform. If you need landscape, undo or a fully offline daily, one of the apps above will serve you better. For short sessions in general, see the best apps for quick games, and every other matchup on the comparisons page.