 However, users who bought the game used would have to pay for the Cerberus Network separately if they wanted access to the new content.This policy allows publishers to combat the used-game market; companies like GameStop have allowed costumers to sell used games back to the retailer so that the company can resell them at a small discount to other customers, but the publisher does not make a profit.BioWare online development director Fernando Melo revealed that 11% of all "Mass Effect 2"s downloadable content revenue came from the Cerberus Network.