cause we totally need purely cosmetic account badges made from those cards?

Nation

It's bugged.

Free to play games drop game cards based on your in-game purchasing history. If you've made purchases in-game prior to the Steam Trading Card Beta, or if you purchased TF2 prior to the Free to Play Update, you'll have 4 or 5 drops available for these games. You'll receive more card drops when you buy items in game, approximately one card drop for every $9 USD spent.

-- from the FAQ

Prior. Sucks.

Anything from the store.

+1, i didn't bought Dota2, still received card ;)

I am almost sure I had the game in my badges list a while after the free weekend was announced.

this^

Same.

Cause you know, Valve has control over how much HIB charges.

or you have a dozen alts idle in it without ever touching the game and sell cards

^

The free weekend?

read the title before posting mate.

Nice didnt even have to do a in-game purchase, whoopdi freaking doo.

Thanks! Guess I have to wait for a beta invite.. Looks fun to find cards!

Too true you can only get so many cards by games. It's more like card sniping/trading.