When I open L4D2, I notice that I have both the L4D and L4D2 campaigns listed as playable missions. Is this because I have both games registered to my STEAM, or do ALL copies of L4D2 include both games, regardless? (plus the sacrifice, of course)

They added all the campaigns from the first game to the second game a long time ago. Last year sometime, I want to say it was free DLC on PC, might have been a small charge on 360.
Tons of fun either way!![]()