Hi! If I wanna do a speedrun of L4D2 with the version 2.0.0.0 how can I do it? Can change my version on Steam or I need to install a pirate version of the game or something?

Hi! If I wanna do a speedrun of L4D2 with the version 2.0.0.0 how can I do it? Can change my version on Steam or I need to install a pirate version of the game or something?