Around 10,000 people have signed up to Scholastic's Horrible Histories virtual world since its official launch last week and the beta testing period over the summer.
Publisher Scholastic intends to develop further "Horribles" portals depending on the success of the initial website, HorribleHistoriesWorld.co.uk.
Lisa Edwards, publishing and commercial director for Scholastic, said: "We will launch ‘Gory Games World' in 2012 in time for the Olympic Games and, if it all goes to plan, we can extend the Horrible Histories world to include other Horribles, such as science and possibly geography and maths."
While the Pottermore.com website is being made available for free, HorribleHistoriesWorld.com will drive revenues through subscriptions and virtual world purchases, using online currency "groats", as well as through advertising.
The number of actual subscribers to the website was unavailable but Steve Richards, m.d. of the site's developer Yomego, said people were beginning to sign up. Subscribers, who will pay £3.99 a month, also get their own room that they can customise, for example an Egyptian tomb or a pirate cabin. Richards said: "Subscribers receive extra benefits such as virtual currency and a number of enhanced experiences, such as games, quizzes and quests."
The big marketing push for the website will take place in September when children return to school. Richards said: "Any brand moving in the virtual world needs to be distinctive and to be spread across a number of areas such as television, books and film or sport." The website should break even within 14 months, he said, adding that companies wanting to develop their own similar environment are looking at a six-figure investment.
The Horrible Histories books are also being converted into e-books and will be available from September. However, Scholastic is not planning to create any apps for the series. Edwards said: "We are steering away from the app market because children aren't reading things in the app space currently. At the moment it is high investment for low returns."