Young people in Habbo, much like a Second Life website for teens, will be invited to respond to briefs for the virtual agency Idea, such as designing adverts and planning events.
The first brief asks users to create a motto for Idea. The National Society for the Prevention of Cruelty to Children is working with digital agency iCrossing to monitor the effectiveness of the campaign before it expands to additional platforms Piczo and Bebo in 2009.
Idea has its own logo -- ChildLine's smiling telephone with a lightbulb -- and will also have its own website once the campaign goes live on December 8.
Ian MacArthur, NSPCC creative director and head of brand, said: "We want to engage children in a meaningful, interactive and fun way with ChildLine, what it does and how it helps.
"We want children to feel that it's their service so that when they need help and support, ChildLine is at the forefront of their minds."