Today I made a Youtube channel to try out the RotT contest GOG is running. After checking back here to see if OldFatGuy ever updated what happened, I did the same tests from when I heard of the two week limit and recorded them to see how uploading videos went.
These are far from professional, as indicated by the Bandicam logo at the top, but it shows the results. When you boot Windows in VMWare, it sets the date to match your host machine. So I couldn't change the date from the VM BIOS. Instead I use the task manager to make sure Steam fully shuts down before messing with the date.
The first video disables the LAN and tests offline mode at 7, 13 and 14 days. When you hit 14 days it locks you out until you have a network connection to re-authorize.
http://youtu.be/J_Wh4xOuANw In the second video I installed a firewall called Net Peeker that has pop up notifications when a program tries to access the internet. After placing Steam into offline mode, turning on the firewall, and moving the date forward 14 days it tries connecting to Valve servers. If you deny the connections it won't let you into Steam. If you allow them it re-authorizes with Valve and then continues loading into offline mode.
http://youtu.be/dF6HiFqP28Q So as is you can stay in "offline" mode, but if Steam can't check back it won't load anymore after two weeks unless it can get a connection again.
isis12: By the way, has anyone figured out what exactly to block with the firewall to cut the connection to Steam? I have tried all kinds of things, steam.exe, steamservice, steamerrorreporter et al, it still sends data. Only blocking internet traffic entirely works. But that's a bit too much even for me.
Here are the IPs that steam.exe tried connecting to when I tested that.
208.64.200.189:27030
208.64.200.191:27030
208.78.164.7:27038
208.64.200.190:27030
63.228.223.110:80
68.142.118.254:80
and steamerrorreporter.exe tried connecting to 208.64.203.140:80
The port 27030 and 27038 seem to be the authorization ones. Try setting a universal rule blocking them and it may work. I don't know if there are any other ones it tires eventually if those aren't available though.