The pound;1.7million site aimed at five- to 11-year-olds allows them to explore an animated world of public services, taking virtual tours of a town hall, hospital, fire station and sports stadium. Girls should find the site particularly inspiring as it features women in traditionally male roles, from firefighter to town mayor.
The site includes lesson plans for citizenship teachers and activities. In one, children are asked to find a name for a police dog.
The Department for Education and Skills said the site has been developed after a government study found Britain was lagging behind other countries in developing a relationship with its young citizens and "involving them in policy making". Early exposure to the government brand would foster trust and interest in government in later life, the study found.
Ms Hughes insisted the site was not just about "marketing government".
"It can give a practical and age-appropriate understanding of another world that will be making decisions that will affect their lives," she told The TES.
"It highlights their rights and responsibilities and what being a responsible citizen means. It reinforces messages that schools will want to give children."
The project was "money well spent", she said, and users could expect to see it develop further in the coming months.
It goes alongside the Directgov website, which provides adults with information on public services.