Steps: 1 - Delete the original left4dead.exe (should be less than 100 KB size) 2 - Copy the left4dead2.exe (File is more than 300 KB in size) file to the left 4 dead directory. 3 - Rename left4dead2.exe to left4dead.exe. You'll notice that the icon switches to L4D1 for some PC's. 4 - Play!

[Node next to the military vehicle] For Left 4 Dead 2, The Source engine received many new features and optimizations that enable it to handle denser, higher resolution environments, effects, and characters. This gave us leeway to fit additional weapons, creatures and larger environments into the same footprint as Left 4 Dead, while increasing the quality of each element across the board. Many of our particle effects use several new techniques which at least double their visible resolution while requiring no additional memory. This has enabled us to create complex weather effects such as heavy thunderstorms in the Hard Rain campaign. The new zombie horde is considerably more variable than that of the first game, with higher resolution meshes and skinning. Not only do the infected look better, but using a combinatorial meshing and shading system, there's over ten-fold the number of variations possible in Left 4 Dead 2 while consuming no more memory. The environments also feature considerably more polygonal density than the first game. Many elements that would have been painted into a texture are now fully modeled in the environment. Foliage looks cleaner while also responding naturally to weather conditions. Additionally, water has gotten a major visual upgrade over Left 4 Dead 1, with far superior lighting, reflections, and flow mapping. All of these pieces come together to improve the visuals of the game while keeping it smooth to play.

Steps: 1 - Download and open the 4gb_Patch.exe 2 - A file open dialog/prompt will appear. Within this dialog/prompt, navigate your local installation directory of left 4 dead and open the left4dead.exe 3 - An "Executable successfully patched" prompt will appear once done. 4 - Play!