UPDATE The original version of this story said that 55 Pixels had been ruled non-compliant, but after speaking to the developer Gamasutra has established that the company came into compliance with ASA standards this summer.
Mind Candy was indeed ruled non-compliant by the ASA, but as of October 28 the company's profile has been removed from the Advertising Standards Authority site. This story from The Guardian also houses a link to the ASA's website which no longer works. You can see a cached version of the ruling here. Gamasutra has reached out to the ASA for clarification about Mind Candy's current status.
An edited version of the original story, with corrected references to the current state of 55 Pixels' compliance, follows:
55 Pixels and Mind Candy, developers of free-to-play online kids' games Bin Weevils and Moshi Monsters respectively, got in hot water with the UK's Advertising Standards Authority in August -- with the agency ruling that the two game developers were in the wrong regarding how they advertised to kids on their sites.
When the agency launched its formal complaint against the pair in August, it said that the two games leveraged "language and prominent calls to action that put pressure on young players to purchase a subscription" -- language which is against its standards for advertising to children.
The agency now says that Mind Candy didn't address the core of its complaints, and the initial ruling is upheld. 55 Pixels has informed Gamasutra that its complaint has been resolved, and its name does not appear on the website's list of non-compliant advertisers.
At the time, 55 Pixels launched a free-to-play-based defense: the company told the ASA "that the website was free-to-play, but that there was a membership option in the form of a monthly subscription. They said that 90 percent of the site's content was free to play and that 90 percent of their audience were non-paying players," the agency noted in its August ruling.
The crux of the issue, however, is not whether the games are largely free-to-play or offer only optional subscriptions; the issue is that certain language -- mainly, direct exhortations to join or pay -- is not acceptable in advertising directed at children, the ASA states in both cases.
Mind Candy was yesterday put on the ASA's website as non-compliant, but that's about the extent of the power the agency has against web advertisements (by contrast, it can get ads removed from television.) It's worth noting here that the ASA is not a governmental body, but an independent organization.
If you're concerned about compliance with the rules, you can check out the UK advertising codes here.