zyngaAfter shutting down offers on its social games because of accusations of scam ads, social game firm Zynga is bringing them back under tighter controls.

Mark Pincus, chief executive of the largest social game company, said in a blog post that the company is taking a baby step to bringing back offers, which are a special kind of ad where a user signs up for a service in lieu of paying for a digital good with money or a credit card in one of Zynga’s games. The company will only use offers from eight advertisers: Netflix, Discover Card, Blockbuster, HSBC Direct, Gamefly, Book of the Month Club, SnapFish and The New York Times. The limitation is meant to ensure that consumers have a good experience.

Zynga shut offers down in November because of a controversy where offer providers were accused of running slimy promotions that tricked consumers into buying services they didn’t want. The controversy provoked self-examination in the industry, led to bans of some offer providers and ad networks on Facebook. It also pushed more companies to adopt strict standards on the kind of offers they would make available to consumers.

But offers have made their way back because consumers like them — at least the good offers. In games such as Zynga’s FarmVille, you can buy things such as tractors to grow vegetables faster. They cost money, but players who don’t want to spend money can accept an offer instead. For those without credit cards, it’s an alternative. And for Zynga, offers have generated a sizable percentage of revenue.

Pincus said that Zynga has set up a team that will check the quality of any offer displayed in Zynga games. The group will follow standards that Zynga has published. As more companies meet the standards, Zynga will add them.

Zynga will also test new brand engagement ads in its games. PetVille will test ads from Visa, Sprint, XBox, Timberland, MTV, TV Land, CW and HTC. This type of brand engagement will allow users to gain currency in a fast and easy way. In these ads, you can get a free virtual good if you do something like watch a video ad.