It resolved itself after being stuck at 0KB for 10 to 15 minutes or so, while I was researching a possible fix.
Then it quite quickly progressed through the download.
Every game present on Steam is broken down into chunks of around 1MB in size.
During World War II Union Pacific operated some of the most modern and powerful steam locomotives ever built.
I'm guessing the "Download failed: http error 0" has something to do with it.
I'm connecting to internet through a router, no proxy needed for other apps.
It takes a long time to find the update, and then it hangs at 0 KB.
The same thing happens in the latest deb as well as the one found in the software center.I had tried a reboot already, which made no immediate difference.