For free-to-play games like Zynga's Mafia Wars, some of the marketing is done by the players and the social networking sites that serve as their platforms. But some of it is done in more direct--and legally questionable--ways.

　　The San Francisco city attorney wants the developer of Mafia Wars to make it an offer. According to a report on the Web site of the San Francisco Chronicle, city attorney Dennis Herrera has threatened to sue the casual game developer for a recent marketing campaign that saw dozens of stickers applied to public sidewalks in five separate locations. The stickers were made to look like $25,000 bills, each promoting Mafia Wars Las Vegas content recently added to the game and directing people to a promotional Web site.

　　The Department of Public Works needed to use a steam cleaner to remove the stickers, a process that took about 45 minutes at each of the stickered locations. Herrera has asked for Zynga to turn over e-mails, contracts, marketing plans, and other documents relating to the campaign. The city also wants Zynga to do more than just pay for the clean up, as it has asked the developer to propose a solution that would "fully resolve" the complaint.

　　"The City Attorney takes violations such as these very seriously and intends to pursue every available cause of action aggressively against Zynga for these illegal marketing tactics," the city attorney's office said in the letter to the casual games maker.