Regular readers of Apps Playground may have noticed that we’re big fans of the storybook apps from British publisher Nosy Crow.

From fairytales like Jack and the Beanstalk and Little Red Riding Hood to animal antics like Axel Scheffler’s Flip Flap Safari and Rounds: Parker Penguin, the company has reliably turned out original, well-crafted apps with a strong focus on reading as well as interactive whizziness.

Now Nosy Crow is trying something new: digital jigsaws. Its new app is called Nosy Crow Jigsaws, with the promise of more than 200 puzzles to piece together on iPhone and iPad.

It’s also the company’s first “freemium” app, meaning it’s free to download, and makes its money from in-app purchases. That’s a concept that has been controversial in children’s apps over the past couple of years, but Nosy Crow’s new app is an example of how in-app purchases can be used responsibly, we think.

So, 200 digital puzzles, using artwork from illustrators who’ve worked on Nosy Crow’s print books – Scheffler included – as well as Ed Bryan, who does the marvellous artwork for the company’s apps.

You get five free jigsaws when you download the app, but then you can also unlock puzzles based on other Nosy Crow apps that you own already – if you bought Little Red Riding Hood, you’ll get its puzzles in the new app, and so on.

Other puzzles are sold in packs of 10 for £0.69 each, or you can choose to pay £6.99 to unlock everything at once. It’s all presented clearly, with a parental “gate” – you have to enter your age – before you can access the in-app store.

“We know how many parents are wary of in-app purchasing – often with very good reason – and we’ve tried to be respectful of those concerns: we’ve implemented in-app purchase with the upmost caution,” explained Nosy Crow’s Tom Bonnick on the company’s blog.

“We’ve tried to be as upfront as possible: there are no tokens, or gold coins, or any similarly euphemistic currency that might confuse a child about whether or not they’re spending real money.”

The app itself works very well, too: you can change each puzzle’s difficulty level from four to 300 pieces, depending on the age and ability of your children. Actually solving them involves pinching to zoom in and out of the virtual puzzle board, while shuffling pieces from a pull-out “tray”.

It’s a difficult idea to get right on a touchscreen – and of course, it’s a different experience from the tactile fun of doing a real puzzle, so we wouldn’t suggest it’s a replacement for that – but Nosy Crow have done a great job.

Nosy Crow Jigsaws is a free download for iPhone and iPad from Apple’s App Store.

Read about more Nosy Crow apps for kids on Apps Playground, and check out our 100 Best iPad Apps of 2013 e-book – £1.99 from Apple’s iBooks Store