Most of these puzzles began in Simon Tatham’s Portable Puzzle Collection, and if you know that collection you will feel at home. This app changes some things on purpose. Here is what to expect.
Items with this symbol are experimental: they work, but they are likely to change in a future update, and might be removed.
Hints explain themselves. Where the original’s hint reveals a move, this app’s tells you why that move is forced, so you can use the technique yourself next time. It can also play a puzzle out a step at a time, and it refuses to guess for you.
Checking your work. Many puzzles can tell you whether what you’ve entered so far contradicts the answer, and will hold a saved position for you once it’s checked out.
Checkpoints let you save several positions within a game’s undo history and return to any of them.
Boards fit your screen. Where the original’s sizes are wider than tall, this app’s are taller than wide, for a phone held upright. On a wider screen, a new board that plays the same either way round is dealt turned to fit.
Links instead of command-line options. The original’s desktop builds take
options on the command line; here the same things go in the address. Add
?type=params to a puzzle’s address to choose a variation, or ?id=id-or-seed
to open a specific game. The
Dominosa, Mines, Net, Pearl, Rectangles and Same Game: the original lets you switch off the check that a new board can be finished (Ensure solubility, Ensure unique solution, Allow unsoluble, and Dominosa’s Ambiguous difficulty). This app has no such switch. Every board it deals has one solution, and outside a level named Unreasonable, one you can reach by reasoning alone. A game ID for a board that needs a guess, or that has several solutions, does not open here.
Light Up: the difficulty the original calls Hard is named Unreasonable here, because those boards require trial and error by construction. That naming is a promise the whole collection keeps: see Difficulty.
Pattern: there is a second difficulty, Unreasonable, which the original does not have. Its boards have one solution that no row or column reaches on its own, so somewhere you have to try a square. The original’s boards are this app’s Easy ones.
ABCD: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that the numbers do not lead to step by step, so somewhere you have to try a letter. The original’s boards are this app’s Easy ones, and what it calls Hard, a board with some of its numbers hidden, is named clues hidden here and can be had at either difficulty.
Crossing: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that no run on its own leads to, so somewhere you have to look across the whole list or try a digit. The original’s boards are this app’s Easy ones.
Filling: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that no forced square leads to, so somewhere you have to try a number. The original’s boards are this app’s Easy ones. A board of more than 300 squares is not dealt: the original goes on trying to build one and, past about 25 by 25, never finishes.
Mosaic: there is a difficulty, Easy, Normal or Unreasonable, which the original does not have. A Normal board is not finished one number at a time: somewhere you have to compare two numbers whose blocks overlap. An Unreasonable board has one solution that comparing does not lead to either, so somewhere you have to try a square. The original’s boards are this app’s Easy ones. A long thin board is not dealt past a length that depends on its width (20 squares at 3 or 4 across, 100 at 10 across): the original goes on trying to build one and never finishes.
Palisade: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that no forced edge leads to, so somewhere you have to try an edge. The original’s boards are this app’s Easy ones. A board in a great many small regions, such as 21 by 21 in threes, is dealt in a few seconds: the original draws whole boards until one has a single solution, which at such a size next to none has.
Separate: there is a difficulty, Easy or Unreasonable, which the original’s unfinished version of the puzzle does not have. An Unreasonable board has one solution that no forced edge leads to, so somewhere you have to try joining two squares. The boards the original makes are this app’s Easy ones. Far more sizes are dealt: the original fills the grid with letters at random until a board happens to be solvable, which next to none is once the grid or the number of letters grows, where this app places the letters so that it is. A 20 by 20 board with two letters takes a second, and an 8 by 8 with eight a moment. A board with many letters on a large grid is still refused, with a reason: at most 13 letters, and from 8 letters only a small grid, such as 10 by 10 with ten.
Signpost: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that no forced link leads to, so somewhere you have to try a link. The original’s boards are this app’s Easy ones.
Sticks: there is a difficulty, Easy or Unreasonable, which the original’s unreleased version of the puzzle does not have. An Unreasonable board has one solution that no forced square leads to, so somewhere you have to try a line. The boards the original makes are this app’s Easy ones.
Net: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that no forced square leads to, so somewhere you have to try a square one way. The boards the original makes with “Ensure unique solution” on are this app’s Easy ones.
Range: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that no forced square leads to, so somewhere you have to try a square. The boards the original makes are this app’s Easy ones.
Rectangles: there is a difficulty, Easy or Unreasonable, which the original does not have. An Unreasonable board has one solution that no forced rectangle or line leads to, so somewhere you have to try a rectangle. The boards the original makes with “Ensure unique solution” on are this app’s Easy ones.
Earlier changes to individual puzzles have since been accepted into the original collection, so they are no longer differences.
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