HL2 and trading cards

If you want to idle, better start the game in textmode (you can run multiple games in textmode!)

You need to either join the Trading Card group and get on the waiting list, or you need to get a spare invite from someone else who already got one this way.

If you can't wait for the group to give you an invite, try here. Currently $0.50 apiece, but will drop when the next round of group invites are doled out...