Out-of-copyright books are providing fertile ground for app developers keen to play with the form and features of novels as apps, as shown by new iOS releases based on Kafka’s The Metamorphosis, Conan Doyle’s Sherlock Holmes stories, and Dickens’ A Christmas Carol.

The three apps – all from independent developers – have different prices and features, with a strong emphasis on illustrations alongside the original texts.

The Metamorphosis for iPad is the most expensive of the three at £6.99, and has been released by developer Joel Golombeck. It packages Kafka’s original text with 35 “original, interactive illustrations”, playing with typography as it goes.

“‘Scenes’ replace ‘pages’ and content can be experienced undisrupted by the arbitrary confines of a physical book’s structure,” explains its App Store listing. “These scenes create an entirely different reading experience, comprised of original Illustrations that become the context in which text can manifest.”

Sherlock Holmes for the iPad has been released by Gutenbergz as a free download, focusing on five of Conan Doyle’s detective tales condensed into 100 “full interactive pages” with music and animation.

“We marry rich interactivity with traditional storytelling to deliver unique reading experience for millions of booklovers all over the world,” explains the company on its website, which stresses that the company is less a developer, and more “a digital publishing house that really loves books”.

Finally, A Christmas Carol Drawn & Told does exactly what its name implies: voice narration of Dickens’ famous festive story accompanied by more than 300 drawings of the characters and action.

It’s the work of developer Alan Snow, and costs £4.99 on the App Store as a universal download for iPhone and iPad.