Needed to asure gameplay:

* Microsoft Visual C++ 2008 SP1 - Download and install: 32-bit or 64-bit // x64 OS users installthem both to be sure, as the game is x32 program (left4dead2.exe *32)
* Microsoft's .net Framework 3.5 - Download and install .net 3.5

I. Install Left 4 Dead 2:

* Extract the files from Dir. using 7zip (winrar was reported to record errors). I recomend this and no other installer since the clean 2.0 was the only one working for me (tested several clients and all failed)

II. Update Left 4 Dead 2:

* Update L4D2 to the latest version using the update installers:
1. Install //The Update will update the client to v2.0.1.3
2. Install //The Update will update the client to v2.0.1.4

III. Install Add-on Support:

Add-on Support Package will allow you to run any custom map,
including the ones released for original L4D.
* 1.Instal
* 2.Instal After, and only after, doing exactly those steps as i described them:
*PATCH THE GAME WITH IV. Patch Game with Rev-Emu:

* Install Latest Rev-Emu Installer which includes left4dead2.exe and Setti masterserver.vdf.(MEANING ). Install to your Left 4 Dead 2 Installation Folder and choose which fix to use (either RevEmu or RevExe).
* Edit rev.ini with notepad to change your name. (SteamUser=YourName and PlayerName=YourName)
* Edit rev.ini depending on how you would like to play:
- For playing single player via the main menu:
Edit rev.ini with notepad and comment out the ClientDLL line with a # like this:
#ClientDLL=steamclient_l4d2.dll
- For playing online and enable serverbrowser and SteamGroupServer on main menu:
Edit rev.ini with notepad and confirm the ClientDLL line is not commented out:
ClientDLL=steamclient_l4d2.dll

Go into your Left 4 Deadbinconfig folder and make sure Masterserver.vdf is set to Read-Only. The latest RevEmu installer will set this to read-only for you.

* Use openserverbrowser in console to open the server browser.
Setti servers will now show up in the custom tab of the server browser.
Favorites tab doesn't work - Don't use it - it will crash your game
SETTI Steam Group Servers will be available via the Main Menu for quick connection to servers!!

V. Play by executing Left4Dead2.exe:

* The latest Rev-Emu installer will create a desktop icon for you.NOTE:
If you previously used Stryder Loader and wish to move to the New Rev-Emu:
1-Remove Stryder Loader: delete stryder.dll, stryder.ini, stryder.txt, IniGen.exe from root folder and remove Name Enabler Addon.
2-Install repacked update with new patched client.dll.
3-Install latest rev-emu.

For further details & help read:
http://blog.theevilpc.com/2009/11/how-to-update-and-play-left-4-dead-2-no.htmlEnjoy the game!

PS:
If you fallowed all this steps, exactly as i described them and the game doesn't work, you've donne something wrong. I tested this on and NOTE!!!

!!! Updated to 2.0.1.5 and it works great, you only need L4D2_Update_2014_to_2015 from the site
http://blog.theevilpc.com/2009/11/how-to-update-and-play-left-4-dead-2-no.html

G3N0™ salutes you.