We can see a lot of activity around Linux lately. Main software developers are going to support Linux in the future, Valve is continuing with enhancing Steam Linux client and Linux graphics drivers are getting better and better. That's just a quick and shortened summarization of what is going on ... there is so much more.
One of the most discussed topic for 2013 is Linux and games. We shall be seeing a huge game developers moving toward Linux this year. Valve games will by finally available on Steam, Blizzard will be releasing at least one of their games and many other smaller companies announced Linux support recently.
It's a smaller publisher releasing mainly strategy games. But their games are popular indeed. You can find the full list here.
Their first Linux push (Crusader Kings 2) was made available on Steam on 14/1/2013. The game was released for Windows and Mac OS X last year and is now one of the most popular Turn-based strategy games.
According to the discussion thread available on paradoxpaza.com forum the company is looking into supporting more titles in the near future. They are probably working on porting all newer titles where it is technically simple (read all games available for Mac) and will be supporting Linux with the majority of the upcoming titles as well.
PI developer answered to my question very positively:
Technically moving from Mac to Linux is "easy" - we will be making Linux a priority as go along. So sooner or later all games where it's technically/financially feasible to do Linux will see linux support.
Their Linux move is very appreciated within the community. They've been asking for proper Linux support several years, now finally happening, possibly thanks to Valve's recent turnaround and Windows 8 disappointment.