Chokkan Hitofude (known from here on as Polarium, the English name for it) is a puzzle game with a simple enough concept. The player is given a grid of black and white squares, and for every square he traces over, the colour is reversed. The object of the game is to make as many horizontal lines as possible match up so that they are all the same colour (either all white or all black, or even a combination of both), thus clearing them.

There are two different modes to Polarium. The first mode is called 'Challenge', which is an endless-style mode, similar to Tetris. This mode is surprisingly difficult right from the start, which may put off players. The aim of this mode is to keep clearing slabs of blocks that are continually falling. The more you manage to clear using just one line, the more advantageous it is for you. However, it can also be quite risky to do so, especially during the later stages when the blocks start coming thick and fast. If the slabs cross over the red bar at the top of the top screen, then it's game over. Every 100 lines, the patterns for the blocks change, each becoming progressively more difficult, thus making it not only slower to trace one line solutions, but harder to think of what they could be.

For those who don't like the frantic Challenge Mode, there is also a second mode of play, called 'Checkmate Mode'. This mode of play takes a much more relaxed approach to Polarium's game mechanic, in that you're presented with a grid which has a set of black and white tiles (often making a picture). It's up to you to make all the horizontal lines either all black, all white or a combination of both by tracing around with just one line. The puzzles start off fairly simple and obvious, but quickly become more devious and tricky as you progress.

There are 100 different Checkmate puzzles in the game, but that doesn't limit the amount that the player has. This is because you can also create your own Checkmate puzzles with a simple-to-use editor. The editor won't let you save a puzzle until you've traced around it and solved it yourself, so it even prevents unsolvable puzzles from being created. Once you're finished, it will save it in the slot you've selected. You can also view a password for the puzzle so that you can give it to your friends. For example, this code:

9526394573

1526946823

0875868104

will give you a puzzle shaped like the capital letter 'N'. There are also puzzles available on Nintendo Japan's website. In addition to giving people across the world your puzzles, you can also send them to someone across the room, using the wireless link-up feature of the DS to transfer puzzles rather than entering a code. Polarium supports Single Card wireless transfer to send a person a sampler of ten Checkmate puzzles as well as the tutorial - just enough to entice them to get their own copy. The game also features a two-player versus mode, but unfortunately two cards are required to play.

Polarium has been released as a budget title in Japan, and its low-key presentation in both graphics and sound confirm this. There are only about two songs in the entire game, and the graphics mostly consist of black and white, with orange also being used. This is by no means a problem, as the graphics achieve what they are intended to do, which is to present the game, while the sound is pleasant and unobtrusive. However, these are not the key selling points for the game. Like Tetris, the gameplay is where it's at.

Polarium is easy to get into, with something for both action-puzzle experts and those who prefer to take their time with puzzles, like crosswords. Its simple presentation may deter players who like a bit more pizzazz and graphical flare, but an entertaining game with lastability awaits those who decide to pick it up.

Polarium will be released locally for the DS in the future, but if you simply can't wait, you can pick up your copy from our partners at Lik-Sang. While the text is entirely Japanese, the menus are fairly obvious.