Trying to find more information about the DayZ mod, I learnt that the base game (Arma 2) appears to have 2 different 'free' versions, one enticingly labeled as 'Arma 2 Free' and also a seperate 'Demo' - however neither the official site nor Steam helped me figure out why anyone would go for the demo version.
To make things more confusing, the Steam download link for Arma 2 Free says 'Download Demo'. I'm aware that demo release was 2009 and Arma 2 Free was 2011; and the features not included in the free version.
So, what is the demo - and does the Steam download for Arma 2 Free actually install just the demo or the full 'Free' version that I could get from the developer's site?

