Millions of Steam users communicate using the digital game distribution client’s chat to not only compare notes about games, but also as a social networking tool. However, Valve Corporation, the parent company that runs the Steam service, has begun to censor private chats between users, deleting messages containing links to websites for downloading torrent files, whether or not these are legal downloads.

Specifically, any reference to a particular torrent site is being stripped from conversation, while mentions of other pages trigger a warning that the site is ‘potentially malicious.’

As per coverage in PlayerAttack, there are indications that Valve is reading the chat between users and searches for specific keywords, particularly Kickass Torrent mirrors. Players discovered the censoring when the website Kickass.to went offline and users noticed their messages failing to arrive when referring to the site.

It’s not clear why Kickass Torrents has been singled out for attention. TorrentFreak also confirmed after running some tests that messages with Kickass.to domain name are posting. It’s not just the domain that’s censored, but the entire message. Steam chat is flagging other domains including Kickass.so, the Pirate Bay and Torrentz.eu as potentially malicious, and users get a warning if they attempt to open them.

Like the Pirate Bay, Kickass Torrents has fallen victim to domain name seizures, and was taken offline earlier this week. It would appear that Steam does not want its users to discuss it in any form.

Steam chat was already often suspected to collect certain data or record the entire conversation. Back in January, Valve banned a number of Counter Strike: Global Offensive (CS:GO) players for allegedly fixing matches to earn money from gambling. Valve banned the offending players from the game permanently and requested that “CS:GO event partners” not allow any of them to play at future events.

Some sites including Kickass.to do host illegal torrents of games, which would motivate Valve with a solid reason to block the contents. Valve might not want to be held liable for whatever legal drama comes of that. Some of those sites can also link through to popups and malware infected adverts, so no doubt Valve wants to keep people away from those too.