Zoo Keeper

There's a cunning trick behind the best puzzle games - they're simple to start playing, but hard to master. Zoo Keeper has the simple part covered, but if hard is measured by your progress on the hi-score table, mastery will take some time to gain.

The basic idea of the game is to line up three or more animal icons on the eight by eight grid on the DS' lower screen which you do by swapping neighbouring animals. As soon as you make a line of three, the animals disappear and more fall down from the top. If you're fortunate, the falling blocks will make further lines to create chains for big bonus points. And as we all know bonus points mean racing up the high score table and that means we're getting masterful.

There are four single player modes. In normal mode, it's a race against time as you line up an increasing number of animals to reach the next level. The tokoton mode is more suitable for long sessions as you have to capture 100 of any escaped creature to level up. In the quirky quest mode, the angry zoo boss will set you a variety of tasks to complete, although he never seems to be particularly happy, regardless of your success. Finally, the time attack mode counts the number of lines you can make within a set time period, which is great for when you've only got a few minutes to spare.

There's a neat multi-player mode too, in which you and a friend race against the clock with your successful animal alignment nibbling away at your opponent's timer. The first one to hit zero is the loser. It's a fun way to go head-to-head, and what's also great that you can share one copy of the game.

As for how the game looks, the graphics are stylish and colourful and when you capture the animal that's your lucky animal, its animation on the upper screen makes you chuckle. The music is catchy as well, if a little repetitive after a while. The action is simply controlled. You can use the d-pad and shoulder buttons if you like, but Zoo Keeper really shows the strength of the DS' unique touch-screen interface. If you want to get on the high-score table, the intuitive and much quicker stylus control is the only way to play.

And this brings us to Zoo Keeper's problems. If your goal is to reach the top of the leader-board, you'll need to beat a score that seems superhuman by anyone's standards! This can be de-motivating if you consistently fail to accumulate enough points to mark your progression. Another minor irritation is the game's failure to include a stand-by mode, employed to great effect in other DS games. This means that you can't snap the DS shut when dinner's ready and resume play at the same point later on.

But despite these issues, Zoo Keeper's simplicity, along with well designed visuals and its friendly style makes it hard to put down, once you've picked it up.