Koloomn could easily be mistaken for a Tetris clone if judged purely on the block-puzzle nature of the gameplay, but this would be quite far off the mark. While Tetris is a rather simple game that deals with falling blocks, Koloomn is all about rotating blocks, creating chains and earning special blocks that can give your opponent huge problems. It's most definitely a game that needs your complete and undivided attention.

The game screen consists of rows of coloured blocks, with your goal being to link up four or more blocks of the same colour. This is done by rotating sets of blocks within a 2x2 grid, with matching blocks being removed from the screen. Once four or more blocks have been linked you have a few moments to attach further blocks of the same colour, with those also being removed if you do so in time. As time passes more rows of blocks will be added to the bottom of the screen, with the game ending when there's no more room to add further rows. That's the basics cleared up, but things get so much more complicated.

A number of magic blocks can be gained by creating chains: where the removal of a set of blocks causes another set of blocks to fall into place and be removed. The more chains you manage, the better the magic block you earn, with four chains giving you a Wave block. This will clear all blocks on the screen that are the same colour as the magic block, making it an extremely useful block to get hold of.

If you're playing in a single-player game mode, this is pretty much all there is to the game, but Koloomn is best played against an AI or human opponent. In versus games attacks are available, with the colour of the blocks you're removing on your side of the screen determining how you attack your opposing player. Each colour has its own associated attack, such as throwing large blocks onto your rival's screen if you clear lots of blue blocks, and reversed rotation controls if you clear lots of green blocks. It really adds a whole new dimension to the gameplay and can result in the shape of a match changing in a few seconds.

Getting to the stage where you're able to think far enough ahead to execute huge combos and chains does take a while, but it's worth the effort. Going even further and understanding and implementing certain attacks where needed will take your game onto an even higher level. With attacks from red, orange or green blocks limiting the speed at which your opponent can combine blocks, and attacks from blue, yellow and purple blocks hindering the block field in some way, becoming a Koloomn master will take quite some time.

A number of solo and multiplayer game modes are included, but most play pretty similarly. The real fun comes from playing against a real life opponent, particularly if you're both well schooled in the ways of the game. AI players are a tad easy to beat once you've got over the initial complexity of gameplay, but setting the difficulty to the highest setting will give lone players a fair challenge.

Attack! Attack!

Rather surprisingly, Koloomn is presented wonderfully, with some brilliant animation for the game's characters and a real vibrant feel to the puzzle sections. There is obviously a limit to what can be achieved in a block puzzle game, but it's unquestionably a charming game to look at. The audio is typically puzzle-like, with some upbeat tunes and a smattering of sound effects, but once again, it's hard to see what more could have been done for a game of this type.

Sadly, while Koloomn's unique gameplay makes it one of the most impressive puzzlers available on the PSP, this uniqueness is also what will put off most players. The tutorials do their best to bring you up to speed on all the gameplay concepts, but you'll need to invest a fair amount of time to get the hang of it all. Played competitively there are few games as intense as this, making the lack of unique game modes more than bearable. If you're after a different take on the block puzzle genre, Koloomn is most definitely worth a look.