Reviewing a game is a pretty simple process - you play it, then you appraise it. Sometimes, if a game is particularly bad, it's quite a relief when you've finished playing it for a sufficient amount of time and can move onto the writing bit - with the help of a thesaurus should you need some more ways of saying 'dull'.

However, sometimes it works the other way around - you don't want to stop playing. This is the category Jewel Quest Deluxe falls into, and is the reason this review is being written at 9pm when this reviewer should be watching The Apprentice.

And while Jewel Quest Deluxe is good, it's not as good as the belligerent Alan Sugar.

But it is good enough to induce that 'one more go' feeling that's the key ingredient to any game. The reason it does this so well is down to its short, clever challenges, which always - on the surface - look achievable, but which are usually trickier than they seem.

While Jewel Quest Deluxe is a simple gem-shifting game, of the type cluttering every gaming machine (you swap coloured jewels about a grid and lining up three or more of the same type causes them to disappear), it stands out because it doesn't just require you to clear one grid after another.

Each level is different - although there are only a set number of challenges which vary just slightly each time. In some, you need to turn the board gold - which means matching jewels on every square of the grid. In others you have to collect a certain number of particular jewels - say 25 blue ones.

In some levels you're up against a time limit which ticks down at the top of the screen. And in others you go up against an AI opponent. In these later levels, both of you take turns and the first to reach the target wins.

It's not the most original of concepts - especially since it doesn't vary a whole lot from its predecessor Super Jewel Quest. But, most importantly, it's very playable with just the right amount going on for a mobile game.

The jewel matching is a test of observation, planning and reflexes. But there are additional elements too - such as the special powers you earn by matching up three gold coins on a level. These can be selected and used at any point during the game to clear specific jewels, or colours of jewels.

That's about it - except there are some extra features thrown in, too. Firstly, the achievements, which are a genuine joy to earn - especially when they're rewarded for such random things as finishing a level with less than 5 per cent of time left on the clock.

Then there's the multiplayer mode, played using one handset. In it, you're given a goal with a time limit and both players take turns to do their best. A typical challenge is to collect the most red jewels within the time limit. Again, it's straightforward yet addictive stuff.

Jewel Quest Deluxe doesn't do much to progress the series. And its Indian adventure story told between levels is something most players will probably skip, even if it's effective at its job of giving a reason for all this jewel collecting malarky.

But it's still a great puzzle game, with addictive challenges and a steady learning curve that helps keeps you hooked. If you haven't played Jewel Quest before, consider it a must have.