Few puzzle games approach the depth and atmosphere of 999: 9 Hours, 9 Persons, 9 Doors.

Developed by Chunsoft, this Pocket Gamer Silver Award-winning title achieves its depth by devoting more time to character conversations and storytelling than it does to hidden-object puzzling.

Now, 999 is ready to open the doors to iOS - but it's leaving its puzzles behind.

Joystiq reports that Spike Chunsoft decided to ditch the puzzles of 999 for the iOS port so it could focus instead on "placing the focus on the story as a visual novel".

Zeroing in

This might not be as strange as it sounds, since there's plenty of meat to the story of 999.

The game begins when players find themselves trapped in a sinking ship with eight random companions, all of whom quickly learn that they have explosives embedded in their bodies.

In order to escape safely, they must play by their captor's rules and engage in a math-based "Nonary Game" which, like the game's title, places a heavy emphasis on the number nine.

Originally, this escape involved puzzle solving. In the iOS visual novel version, however, there will be a comic-book style presentation and multi-path flow chart that lets you hop to different parts of the plot.

While the iOS version has only been confirmed for Japan at this time, 999 writer and director Kotaro Uchikoshi expects that an English version "will also be released by autumn".