This is Sid Meier's Civilization Beyond Earth (Mac), but as we know with Civ5 from MacStore, it works fine on other platforms. I've purchased from the link, redeemed with Steam, downloaded, and am currently playing it on my Win7 machine - it works. Why they sell a separate MAC edition is unknown to me, but Nuuvem currently have it on special for R$59.99, this works out to about AU$27.
In the last few days I've seen games which I was still on the fence about purchasing go Region Locked, this one still remains free but probably wont for long ….. then again I could be wrong.
Also, Nuuvem have a big sale on - it's the big wooden De Ano sign on their main page. They have some awesome specials on, but make sure you open the game in a new tab to check if it's Region Locked (e.g. Shogun Total War). As you go down the list and select games it adds them to the side bar, but this is not your Cart so don't close the window. Can only get a max of 20 games at once, as I discovered :)