Wednesday, February 20, 2013

Review: Khalou for iPhone and iPad

Khalou is a very nice free puzzle game for iPhone and iPad by Aurelien Wenger.

The instructions are only in French, so understanding the rules might be difficult, but don't despair! I'm here to help.
The game is played on a 4x4 board, filled with stones. Stones are white on one side and black on the other, and are randomly placed at the beginning:
The goal is to make all stones white. This is done by making a number of moves, where all the stones in a group are turned upside down.
As you can see in the instructions page, the only allowed moves are:
  • Turn all 4 stones in a row, column, or major diagonal;
  • Turn all 3 stones in a L shape, anywhere on the board.
The instructions continue with an example:
At the top is the start position. Then the first and second columns are toggled, leading to the position in the middle. Then a L-shape in the center of the board is toggled, leading to the bottom left position. Then the final L-shape leads to the solved state in a total of 4 moves.

Now if you think about the rules for a moment, you'll realise that the L-shape moves would be all that's needed to solve the puzzle, because there is a sequence of three L-shape moves that toggles a single stone, and could be applied all over the board (figuring out the sequence is left as an exrcise for the reader).

The interesting thing is that, with the full set of rules, all positions can be solved in a maximum of 5 moves. It took me some time to get the hang of it, but when it finally clicked, attempting to always solve the puzzles in no more than 5 moves is an interesting—and difficult—challenge.

The game also has a scoring mechanism, if you're so inclined. When you start playing, you have a time limit of 5 minutes. During that time you must solve as many puzzles as you can; for each puzzle solved, you score points depending on the number of moves and the time taken. But be careful, because if you take more than 5 moves, your score is always 0. At the end of the 5 minutes, your total score is computed and uploaded to Game Center.

Overall, this is a nicely presented way to flex your brain muscles with come challenging, but not overly difficult, logical reasoning.


Logical Reasoning★★★★☆
User Interface★★★☆☆
Loading Time★★★★☆
Saves Partial Progress
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