MarpleCurrent Version: 2.1.8 (iOS 4.0 Tested)

Sudoku-style puzzler proves both challenging and addictive

by Dan Frakes, Macworld.com

One of my favorite things about the iPhone and the App Store is the plethora of inexpensive time-killers available. For just a dollar or two—and oftentimes for free—I can download an entertaining game that will keep me occupied while waiting in line or taking the train to the office. For the past month or so, my favorite such diversion has been the logic game Marple. According to its developer, Marple was inspired by the Palm OS game Hercule, although Marple takes advantage of the iPhone’s touchscreen to offer far better graphics and a better interface.

Marple’s playing board consists of four rows and five columns. Each row hosts a different type of tile: letters (A, B, C, D, E); numbers (1, 2, 3, 4, 5); dice-side numbers (1, 2, 3, 4, 5); or shapes (square, arrow, circle, star, and plus). At the beginning of a puzzle, each column contains one of every possible tile, grouped by tile type (five tiles per row for a total of 20 tiles per column). The object of the game is to figure out which of each type of tile belongs in each column; each tile can appear only once on the board.

Before and After: A new Marple puzzle (left) and the same puzzle finished (right)

For each group, you choose a particular tile by tapping the group to enlarge it and then touching and holding the desired tile. Alternatively—and much more usefully, given how you determine which tile goes where—you can quickly tap individual tiles in the group to eliminate them. You restore an individual tile by tapping it again. Tapping outside of the enlarged tile group “closes” it.

And how do you determine which tile goes where? By using your powers of logic. At the bottom of the screen, Marple provides several types of clues (not every puzzle will have every type of clue):

• In-between clues: Consisting of three different tiles, these clues indicate the horizontal order of the three tiles. For example, 3E2 indicates that E is in a column between 3 and 2 (but not necessarily adjacent to either). The sequence can appear left-to-right or right-to-left.
• Left-of clues: Showing two different tiles with an ellipsis (…) in between, these clues indicate that the first tile is positioned in a column somewhere to the left of the second (although, again, not necessarily adjacent to it). For example, 3…2 tells you that the 3 tile is somewhere to the left of the 2 tile.
• Next-to clues: Consisting of one tile in between two of another tile, these clues tell you that the two tiles are in adjacent columns, but it doesn’t indicate which is to the right or left of the other. For example, 3E3 means that the letter tile E and the number tile 3 are in columns directly next to each other.
• Same-column clues: Showing two different tiles with an up/down arrow in between, these clues reveal tiles that must appear in the same column. For example, 4[arrow]C means that the 4 and C tiles are directly below/above each other.

Guess Again: Use the clues in Marple to eliminating possible tile values.

You use these clues and some clever logic first to eliminate possible tile values, and then to determine which tiles go where. For example, because the middle tile in an in-between clue must be positioned between two other tiles, it can’t appear in the left-most (first) or right-most (fifth) column. You can similarly use left-of and same-column clues to narrow down the possibilities for each group of tiles, making the in-between and next-to clues more meaningful. Clues can be dragged to reposition them; for example, to put clues relating to a similar tile together. And if you no longer need a clue, you can tap it to dim it (another tap undims it). This may sound complicated, but you get the hang of it after a few games. And if you get stuck, the developer provides some tips for beginners in the game’s excellent Help screen, and a Hint button highlights the clue that will be the most helpful at that moment.

Once you’ve chosen a value for every tile group, Marple either congratulates you, if the solution is correct, or tells you you’ve made a mistake; in the latter case, a restart button lets you start the puzzle over. Every puzzle has a single unique solution, and every puzzle can be solved using only the provided clues.

Marple is a challenging and addictive game, and with 1 million unique puzzles, you won’t run out anytime soon. (It’s worth noting that I’ve played more than 120 puzzles so far, and the difficulty level hasn’t changed considerably; I’ve just gotten faster at solving them. This may be good or bad, depending on your point of view.) It also offers several gameplay options in its settings screen. You can enable Warnings, which alert you whenever you choose or eliminate the wrong tile; Auto Deduce, which auto-chooses a tile when you eliminate all other instances of that tile, or eliminates all other instances when you choose a particular tile; and Auto Sort Clues, which sorts clues by type. You can also make the game easier by enabling the Give Away Two Tiles option, which solves two tiles for you when starting a new puzzle. Finally, you can manually jump directly to a specific puzzle by providing the puzzle number.

Time Stops for No One: As you progress with your puzzle, a timer on the bottom of the screen calculates how long it takes you to come up with a solution.

Since every puzzle has a solution, your skill at Marple is based on the time it takes you to solve each puzzle. Your 10 best times, along with the puzzle number, number of mistakes, and number of hints used for each, are saved to game’s Top 10 screen. (This screen also displays your total games played, total time played, and average time per puzzle.) Because each puzzle has a unique puzzle number, you can compare your time on a particular puzzle with those of your friends. Unfortunately, there’s no pause feature and the game’s timer doesn’t stop if you access its settings, Help, or Top 10 screens. Similarly, if Marple is running and you press the iPhone’s Sleep button, Marple’s timer continues to run; I’ve woken my iPhone to discover a puzzle with a two-hour—and running—timer. These inflated times also affect your average-time statistics. The timer should run only when you’re actively playing the game.

The other feature I’d like to see is Undo. I occasionally tap the wrong tile accidently, but if I’m not paying close attention I don’t know which, so I can’t restore that tile group to its previous state. Similarly, if you have Auto Deduce enabled, accidentally tapping the wrong tile may automatically deduce the states of other tiles, so even if you correctly restore the original tile, the auto-deduced tiles aren’t restored.

But these are minor complaints about an otherwise excellent game. If you’re a fan of Sudoku-like games of logic, but you’re tired of looking at 9-by-9 grids, give Marple a try. But be warned: Once you start playing Marple, you may not be able to stop.

Marple is compatible with any iPhone or iPod touch running the iPhone 2.x software update.

[Senior editor Dan Frakes reviews low-cost software for the Mac Gems blog.]