Trixel is one of those devious little gems which looks so utterly straightforward on the outside that you expect to lose interest in minutes.

Don't be fooled. If you're fond of bright clean colours and grid puzzles, this is the iPhone and iPod Touch's equivalent of a suitcase-full of crack cocaine. Except nowhere near as expensive.

Here's the need-to-know: you flip the tiles on a board to match the pattern in top-left. Your cursor can only move one square at a time horizontally or vertically, and you can only move it a limited number of times per puzzle.

There are 100 of these puzzles, plus four race-the-clock challenges and a generous handful of secret levels. At set intervals the game introduces a special tile, like the bomb, calculated use of which is key.

We're hooked, plain and simple. Hit the jump for a video. Or just buy it.