Steam, the popular online game store and multiplayer platform developed by Valve, has been hacked. Valve's co-founder and managing director Gabe Newell, yesterday notified Steam users that the breach may be more serious than initially thought. Though many reports say Steam has notified all of its users, I haven't received any official word. Unless I'm expected to read the notification via TechCrunch's PSA. On November 6th, Steam's community forums were defaced and subsequently shut down for security reasons. Then, the company discovered that hackers had managed to gain access to a database containing information such as user names, hashed and salted passwords, game purchases, e-mail addresses, billing addresses and encrypted credit card information. The investigation hasn't revealed any credit card misuse for the time being, but Newell says Steam users should keep close track of their card activity and statements nevertheless. The company didn't reveal how many of its 35 million active user accounts were affected. Here's the text of the notice on TechCrunch:

Dear Steam Users and Steam Forum Users, Our Steam forums were defaced on the evening of Sunday, November 6. We began investigating and found that the intrusion goes beyond the Steam forums. We learned that intruders obtained access to a Steam database in addition to the forums. This database contained information including user names, hashed and salted passwords, game purchases, email addresses, billing addresses and encrypted credit card information. We do not have evidence that encrypted credit card numbers or personally identifying information were taken by the intruders, or that the protection on credit card numbers or passwords was cracked. We are still investigating. We don’t have evidence of credit card misuse at this time. Nonetheless you should watch your credit card activity and statements closely. While we only know of a few forum accounts that have been compromised, all forum users will be required to change their passwords the next time they login. If you have used your Steam forum password on other accounts you should change those passwords as well. We do not know of any compromised Steam accounts, so we are not planning to force a change of Steam account passwords (which are separate from forum passwords). However, it wouldn’t be a bad idea to change that as well, especially if it is the same as your Steam forum account password. We will reopen the forums as soon as we can. I am truly sorry this happened, and I apologize for the inconvenience. Gabe.

Earlier this year, Sony's gaming platform, PlayStation Network, was hacked, exposing the data of millions of users. The network was disabled for more than a month in some regions. In contrast, Steam has only disabled its community forums. Its multiplayer platform is still running as usual and the user experience hadn't been disrupted.