WARNING:
BACKUP your pak01_dir.vpk and scripts folder before replacing them, the mod files will make L4D2 campaigns crash at the beginning, you'll just have to switch between the original and the one in the pack depending on what you want to play.

If you already replaced it, just delete pak01_dir.vpk and on steam verify the game cache for L4D2, it will redownload.

Step 1. Fixing textures and models

- Copy over all of the vpks from your ../Steam/steamapps/common/left 4 dead/left4dead/ folder to some temporary folder.
- Rename all the pak01_xxx.vpk and pak01_dir.vpk files to pak02_xxx.vpk and pak02_dir.vpk respectively.
- Move the renamed files to ../Steam/steamapps/common/left 4 dead 2/left4dead2/

Step 2. Copying the maps and fixing sounds

- Copy the following folders from ../Steam/steamapps/common/left 4 dead/left4dead/ to ../Steam/steamapps/common/left 4 dead 2/left4dead2/ :
---- maps
---- reslists
---- sound
---- scenes

(When asked if you want to merge folders select "Yes to all", when asked if you want to replace files select "No to all")

Step 3. Bug Fixing
Thanks to myself and Smashman, this is all you gotta do, extract to the common folder and replace all:
http://www.mediafire.com/?nymzmytyt40

After that, download the latest patch and extract it like you did for the above, REPLACE ALL:
http://www.mediafire.com/?2odjdjzofzv

Step 4. Play

- Open up L4D2.
- Type in console: snd_rebuildaudiocache, it will take a long while, if it gets to 100% and doesn't exit you can just ctrl+alt+del and restart the game after.
- The L4D1 campaigns will appear in addons.

UPCOMING

All that is left to do is making L4D2 weapon and item spawns on the old maps.

If you like this mod, join the Steam group:
http://steamcommunity.com/groups/left4modders

Maybe we'll convince Valve to do a proper conversion.

The Pak01 to pak02 is a sure way to get Run time errors. I still think the editing the model names is a better way of doing it.

Nice tutorial though.

Is that Windows XP, Vista or 7?
Also nice job at finding the entity names for the new weapons.
Can't wait to play the old maps with the new stuff.

Hmm Technopath when I right click my L4D2 and Steam.exe files I cant select run as administrator, the option on both exes is dimmed out.

I am the only account on this PC and I am setup as administrator, also using Vista.

If you do the crashing step the runtime errors don't happen, I tested on Dead Air 1 where I was crashing a lot, and after doing that it never crashed as well as Death Toll 1 which was also crashing, they might also be caused by the l4d1 common infected models and the missing sounds, which the tutorial solves.

I'm at work right now, once I get home I'll get started replacing weapon and item spawns, with the following "scheme":

- Some Tier 1 L4D weapon spawns will be replaced with some L4D2 Tier 1 weapon spawns.
- Some Tier 2 L4D weapon spawns will be replaced with some L4D2 Tier 2 weapon spawns.
- Some moltov/pipebomb spawns will be replaced with boomer bile bomb spawns.
- Some pistol spawns will be replaced with melee weapon spawns.
- Some medkit spawns (except the safehouse ones) will be replaced with Incendiary ammo, Explosive ammo, Laser sight upgrades and Defibrillator spawns.

Edited:

I'm using Windows 7 and I have the same problem, just go to the security tab, select your username account instead of the admin one (there will be 2, one for admin and another with your username) and edit the permissions to allow all.

I have no option for Permissions when I do this, it is also shaded out. I have UAC disabled aswell because its just a pain in the ass on Vista.

I also have no CSC folder.

what are the entity names of the new stuff?

im being spammed on steam by someone who wants to know

Just tell them to open a finale bsp from L4D2 in wordpad and search for "weapon_"

thanks brah i knew i could rely on you

Maybe even better would be for him to open the Dead Center map with the weapon store, since that map has all the weapons and items.

Well Ive gotten 0 done on this tutorial. I transferred over the files but I cant use run program as administrator because the box is dimmed out and doesnt give me the option. I also have no directory in C:\Windows\CSC, windows says it doesnt exist at all.

I assume you still crash after doing the other steps (with exception of the crashing ones)?

I cant change Admin privileges on any of the exes, doing what you said earlier doesnt work.

Im not doing low violence.

Im going to try Method 1 right now and see if deleting the NCF files does anything, but I dont see how this would help.

Method 4 is impossible because there is no such thing as the CSC folder on my PC.

I was asking if you skip the crash solving steps and do just the others, do you still crash? Because I think the crash was caused due to missing reslists and sounds, and the new gibbing system messing up with the old infected models.

Also, someone must be really angry with me, rating me dumbs and all, I'm so sad

Whoo, this has made L4D1 even more redundant.

Well, considering only the people who own both games can do this, who cares?

Technopath you just mashed my methods together that will not work, Everyones gonna bitch at you.

I think I merged only method 2 and 4, and both together worked for me, although the crashes might have been caused by missing files which I fixed.

I gave you a Rainbow.

I tried method 1 and am still crashing, Method 2 and 4 will not work for the reasons stated earlier.

I wonder if replacing the L4D1 infected models with L4D2 infected models would do anything.

I can't really say what causes the crashes, by copying the folders I said in the OP, merging but not replacing, the common infected from L4D2 spawned instead of L4D1 ones and I got no more crashing.

I dont get how that fixed it, I ran Crash Course and none of the L4D1 infected spawned. The end finale doesnt work though.

I switched to Death Toll and the old infected spawned again.

That's strange indeed, all the maps are loading L4D2 commons for me after doing that, did you copy over the sound, etc folders too?

Yep and I just rebuilt Soundcache, going to try again.

Edit: Loaded No Mercy 1 and crashed from a runtime error, original zombies with neon clothes spawned.

I might have forgotten to list a folder, although I'm not sure, I wrote the tutorial from memory when I got back to work after lunch, but when testing it at home everything was working fine, expect more news in about 1 hour and a half, just in case I missed something.

I got an idea.

Im going to edit the L4D1 reslist files I copied over and replace all models/infected with L4D2 models/infected

Ill let you know if this works.

Edit: Nope not at all the maps still spawn Neon zombies and crash my game.

Oh, I think I opened up the "all" reslist from l4d1 and copied the content over to the end of the "all" reslist of l4d2, then saved. I'm not sure but I'll check once I get home.

Ok just did that, going ingame to try again. If this works I love you.

Edit: Once again same thing as usual happens.

Try also copying over the content from the l4d1 whitelist reslist to the end of the l4d2 whitelist reslist.

My friends tried just what I said in OP and it worked for them with just that.

Now, how do you play other maps in L4D2 ?

After doing this, you should be able to play any L4D1 custom campaign/map in L4D2.

Ok I did that and it still crashed.

I got the bat in Dead Air too, it must just be the AI director spawning it 50 units or so to the side of your character or something.

Yeah, Valve said that L4D2 would scatter some stuff around to reward exploring, these are just item spawns made by the AI director.

Check my above post. Edit in the Missions folder for running the L4D1 campaigns through the Addons menu, or you could mention that and post the link to the Missions.rar file. Maybe somewhere under your Step 3?

I read it, I'll be doing it for versus first before adding it, while working on the l4d2 entity spawns I came accross viewmodels for the L4D1 survivor arms :D

No point doing it for Versus seeing as not everyone will have installed the l4d1 content the same way. Id focus more on Single player for now and wait for the Authoring tools within the next week.

I dont have a "Run Program as an administrator" option in the compatibility tab, and I don't have a CSC folder. Im on XP.

3 Freaking threads?

I think its because of all the different ways to do this.

Can't we just make a a megathread sort of?