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.