Starting EA Origin in Offline Mode

From this forum thread, the parameter is "Origin.exe /StartOffline".

Using Origin on Wine is BAD NEWS... maybe not?

It seems that most of the issues with this are due to the fiber optic line that broke causing internet issues and DLC authorization errors.  Make sure that all Origin executables on Windows is in your antivirus/firewall exception list.

I'll keep this brief. Over the past days, I had issues with Origin when playing Mass Effect 3 online where connectivity is just shot. I would get errors where Origin would complain not having internet connection.  Mass Effect 3 wouldn't go online either which caused DLC authorization errors.

As it turns out, I started logging into Origin using my Wine install and I noticed doing this would create connection issues on Origin. Once it all got sorted on Windows, using it was fine. So, I deleted Origin on my Wine install. Never again.

Playing Sims 3 on Origin Offline

I'll keep this brief.  I lost my internet connectivity all morning and thought it was a good time to test Origin and Sims 3.  All that I've seen online suggests that Sims 3 will only work online due to Origin's insistence of logging in when running the game.  So when I ran Origin, it gave me a login window and a note that Origin was not available (due to the internet).  I logged in anyway, and then Origin went to my library but also setting the client to Offline mode.  I was able to launch Sims 3 and Mass Effect 2 like this without issues.

A small note on Mass Effect... you will not be able to connect to the Cerberus Network.  You will get an error message but you'll be able to load your save just fine.