The company has already signed up brands such as Coca-Cola, Intel, Paramount Pictures, T-Mobile and Universal Music Group to advertise in 40 games from 10 major publishers.
The ad strategy targets the millions of 18- to 34-year-old men who spend an average of seven hours a week playing computer games online.
Massive Network places images of products or virtual billboards into the fabric of the games.
"Unlike their consumption of television and other media, gamers are 100% focused on the game in hand," Mitch David, the chief executive of Massive Incorporated, the agency's parent company, said.
Massive Network, through its partnership with the online statistics company Nielsen Interactive Entertainment, can supply accurate viewing data for its in-game advertising and also offers planning for campaigns.
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