It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

Recently, I decided to reinstall this from scratch and deleted the Game Preferences folder in app support on my mac. Unfortunately the automatic update that I think It use to have has ceased to work so I was left at the v33 it stated on GOG.

The out of date version led to the game not being able to login to the in-game server for multiplayer(single player still worked if you selected offline but it was still out of date).

Thankfully I had a link to get the newest version(v35) through mode7's site through a humble bundle email. I'm not sure how easy or hard it is to get from their site without said email since I don't know if how their key system works now(I've seen reports that it's different/not used in the same way).

An updated GOG version is needed so I only have to run the 2 installers(base game + red DLC) to unlock the red mode offline without having to login and so I can login if I choose to(the outdated version will not login).