Valve has had to deactivate 1,341 Steam keys for Natural Selection 2, a result of a scam that saw developer Unknown Worlds Entertainment out a total of $30,000. These 1,341 keys were purchased through the developer using stolen credit cards. The real credit card owners made chargeback claims on the fraudulent charges, and as a result the developer never received its money and was instead hit with the $30,000 fee to recoup the stolen funds.

Essentially someone "purchased" keys through Unknown Worlds, sold them to third parties at a discount, then when the original credit card holders emerged and disputed the initial charge to Unknown Worlds, the thief pocketed the cash and made off into the night. As a result, Unknown Worlds has temporarily closed its store, meaning the only eligible place to purchase Natural Selection 2 is through Steam at the moment.

As of today, anyone who purchased those illegitimate keys will find their game deactivated. Unknown Worlds suggests contacting the site you purchased the key from for a full refund - good luck with that!