The Trading Card system will be locked away from new releases on Steam until they have have proven themselves to be real games.
Many games offer Trading Cards which can be sold by players on the Steam marketplace. Their value is typically low, often around 10p or less, although some can go for more. Developers then get a small cut of the sell-on fee.
However, it seems that some developers have been playing the system for financial game, dishing out thousands of Steam keys to bots which then acquire and trade the Cards on their own, generating a little revenue even if no actual gamers are playing the associated titles.
In an effort to combat this, Valve is creating a 'Confidence Metric' that will prevent games from dropping Trading Cards until it can be sure that the title is actually being played by real people.
We added Steam Trading Cards in 2013. We knew some players wouldn't care about them, which was fine - they could simply throw them up on the Steam Community Market, and use the results to buy some other game,” Valve said. For developers, they were an easy way to add extra value to their game, and provide rewards to their biggest fans.
After the release of Trading Cards, the number of players interested in them grew significantly, until it reached the point where the demand for cards became significant enough that there was an economic opportunity worth taking advantage of. And that's when our group of bad actors arrived, aiming to make money by releasing 'fake' games on Steam.
We could restrict the ability for developers to generate Steam keys for their games, but we hate to degrade tools that legitimate developers are using to make their players happy. We're also not certain it would actually solve the problem - there are many ways a bad actor could try to get their game owned by all their bot accounts, and they just need to find a way to do it that costs less than they're making from selling their Trading Cards.
Once a game reaches that Confidence Metric, cards will drop to all users, including all the users who've played the game prior to that point. So going forward, even if you play a game before it has Trading Cards, you'll receive cards for your playtime when the developer adds cards and reaches the confidence metric.”