Five minutes
Flow, Memory Match, Emoji Riddle, a Trivia round, or one of the seven arcade games.
If you would otherwise be buying a puzzle book off a newsagent’s shelf, this is the same idea with 32 kinds of puzzle in it and no last page. Some take two minutes. Some take an evening. You pick which, every time you open it.
The most useful thing about a big catalogue is that your mood gets a say. There is no single difficulty setting the whole app is pinned to — every puzzle carries its own tiers, and most of them go from genuinely gentle to genuinely hard.
Flow, Memory Match, Emoji Riddle, a Trivia round, or one of the seven arcade games.
Sudoku, Nonogram, Minesweeper or Tessera.
Logic Grid, Kakuro, Spider at four suits, or a full Solitaire deal.
The generated puzzles are checked before they are dealt to you. A Sudoku or a Nonogram is verified to have exactly one solution; Minesweeper boards are built so they can be cleared without ever guessing; Gridlock’s par is the true minimum for that board, measured rather than estimated. If you are stuck, it is because the puzzle is hard, not because it is broken.
The card games are the honest exception: a Solitaire or Spider deal is a real shuffle, so not every one can be won — the same as it is with a physical deck.