Valve has revealed that their Left 4 Dead franchise has sold over 12 million copies.
One of the firm's lead writers Chet Faliszek said the series had originally sold better on console than on PC, but it's "probably about even now." He also said Left 4 Dead 2 attributed to a large portion of the 12 million sales, with the sequel having "sold significantly more copies than 1."
Faliszek also touched on Valve's approach to promoting its games; he stressed that the firm doesn't focus nor rely much on marketing because "when a game does really well at pre-release, they're going to know that you're not just talking a bunch of PR crap."
Valve is currently integrating Steam Workshop into Left 4 Dead on PC, giving players the ability to create new outfits for characters, as well as new game modes and more.