Steam Summer Sale 2013

I bought a few mystery cards for a few pennis to see what they'd do.
Now i reget not hoarding some to easily get a high level badge.
o well.


Also, i've never played a Civilization game, do i need to play any of the previous to play the newest or are they non-related as far as story or campaign or whatever goes?
It looks interesting.

Edit: Would appear the individual card prices are already nearing sub 1€
Edit 2: Also you get a card evertime you vote for the community choice if your steam level is above 5, and if you hit level 5 during the event you get all cards you would've gotten.

There isn't a story to Civ games, it's a simulation/turn-based strategy game where you pick a civilization to start with and develop them into whatever you want.