Dr Shaneman wrote...
Oh right, Sonic Rivals has something like that where you won cards during the game you could trade with other people. Never really understood the point myself.
Steam features this as random drops for certain games during playing them.
I think Steam can generate nice profits through Market sales (they get I think 10 or 20% of those)
If you have a full set of cards for a game you can craft them into a badge and gain new emoticons, Backrounds and occasionally Coupons for oher games