Every single one of Steam’s connection manager servers are currently on fire, and it has little to do with their ongoing sale. Based on unofficial server updates from Steam Status on twitter (affiliated with SteamDB, rather than Valve), this began around 7.30am US Pacific Time.
Update: As of around 11.00am Pacific, Steam seems to be back up. The rest of the original story follows.
Update 2: Steam DDOS Twitter account suspended.
As long as all Steam connection servers remain down, nobody, in any region, will be able to connect to the service. Offline mode should function as usual, so any games that do not require ‘phoning home’ to a server should be playable via that method.
Thanks to Valve’s usual stellar communication, there has been no official statement from the company at this time. We’re sure that their workforce is working around the clock to get the servers up and running aga… haha, who are we kidding? It’s basically Christmas, so Ted the intern is probably having to deal with all of this on his own.
A DDOS attack looks to be the probable culprit for this down time. Steam’s servers are seeing absurd amounts of traffic (much higher than usual, even for a sale), which tends to be indicative of this sort of thing.