I got a booster pack without playing the game

No. It's just random. You playing a game had nothing to do with it. I just got a booster while picking my nose. Does that mean you only get booster packs when picking a nose and every other possibility becomes untrue?

Just got a Trine 2 pack for playing TF2, so yes, you can get any booster pack for only having Steam running.

You don't need Steam running, you just need to log into Steam once, and for the next 7 days you're eligible for booster packs.

Send it back to gaben@valvesoftware.com

10 lvl > 20% for booster pack ,
20 lvl > 40% for booster pack....
It's totally random

Apparently there is a booster pack wave spreading around. I just got a portal 2 pack, and another friend got a magicka pack within minutes of each other.

Yeah I got a CK2 one, doesn't sell very well it seems but, worst case scenario I use it myself, and I am actually planning on making a CK2 lvl5 badge + foil one, sometime.

yes, i got it also , when playing other game

You can't get a booster pack before collecting all the game cards...

And if he haven't played this game, he didn't collect any cards. The hell?

yes, you get them even if you aren't playing any game...
apparently those things are delivered on a certain date, at certain time. a lot of people just get a booster pack.

They drop randomly for games with no card drops left. You have to log in to Steam at least one a week to be eligible

I just got a Super Meat Boy pack and I'm not even currently in any game. I just have steam open.

Completely random, as long as you have games in your library that feature trading cards then you're eligible to get booster packs for them (as long as you've gotten all the drops, that is).

Got a portal booster pack while playing borderlands 2 :D

Its very surprise for me because firstly I've got one FS Booster Pack

Got a booster pack while I was sleeping. You don't have to do anything to get the booster packs, aside from log in to steam once a week.

today I got alan wake booster pack :3 and few days ago I got CS:GO booster pack :>

So I don't need to do anything to get them?

Also how on earth does one craft o.o

I got psychonauts booster while I was offline ...

I got the portal 2 booster pack without completing my card drop last week.

I didn't read much ,but do i need to keep the game installed to get a booster pack for it or can i delete it? (need space to play other games and get cards xD)