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We've seen the Left 4 Dead SDK be used to create some truly impressive, zombie-infested levels, but this one might just take the cake. —Griffin McElroy (

Archive for April, 2009


Balancing the difficulty

Posted by Geoffroy in Development, Media, Progress

Tags: , , ,

Two weeks ago, we talked about the manor level and why we decided to do things the way they are right now. This week, the focus continues on the third level, the underground and on the overall campaign difficulty.

When Nicolas wrote the game design document about the campaign, one of the key elements was to build a rather long campaign with changing environments and gameplay. The goal was to provide players with a non-monotonous campaign that would work perfectly well as a whole, but also when playing each level independently. The global path had to be logical, but the gameplay type (open space/close combat) and the environment (exterior/interior) had to change beetween each map, following this approximative pattern :

Gameplay and environment evolution

As you can see, when you combine the different elements that make a Left 4 Dead level more or less difficult, we get the overall difficulty of each level. In game, this is pretty much correct for the moment, when testing we feel that each map is as difficult as it should be, and the third map is really difficult. Much like every official campaigns, we tried to balance the difficulty around the third map. The campaign starts slowly, progressively reach a crescendo at the third map (No Mercy’s sewers, Death Toll’s church, Dead Air’s construction site, Blood Harvest’s bridge) and slows down until the final arrives. But our third map is really hard.

At start, the underground level was supposed to be a catacomb-ish level, with crypts, coffins and all the extra cliché things you can think about. But when the prototyping time came, it was clear that it would never work the intended way. No one would ever want to walk in an endless network of catacombs and crypts during half an hour, plus that didn’t seem very realistic from the start. That’s why we decided to mix several underground environments in the same level. This choice was not really popular among the team until we all actually saw the result when the level reached a decently polished state. The different environments blended together perfectly well and if you didn’t pay attention to it, you didn’t even notice the changes until the end. For the moment, the level is composed of four different underground environments and architectures.

Iterative screenshots of a part of the underground level

The underground level was entirely made in a really short time, I’d say three weeks. Prototyping, gameplay tests, architecture and prop flooding were all completed in a matter of weeks. The only problem with this level is its length. For the moment, this is the longest level I ever played on Left 4 Dead. Taking the shortest path, it takes 3 minutes to run from the beginning to the end, while it only takes 2:25 on the longest Left 4 Dead level (No Mercy’s sewers, which is already a quite difficult level). For the moment, we believe the map is good as it is, because we’re able to finish it using the expert difficulty, but we are not against the idea of cutting a whole part if it’s really too long and difficult.

One of the key elements of making a level more or less difficult without interfering too much on its length and geometry is to tweak the item/weapon spawning. Unlike Left 4 Dead official campaigns, we decided to give more than 4 first aid kits in this level. Because the crescendo event is located in the middle of the level, you often reach it in an already bad shape… thus, you leave it in a terrible shape (if not dead), and there’s a whole half of the level left to do. That’s why we decided to give more than 4 first aid kits, because we know every player isn’t the best player in the world. The trap here is that we’re not really giving 4 extra first aid kits just before the crescendo event, so there won’t be enough for everyone… We believe it will force players to play efficiently and work as a team (or they will just insult each others and keep their first aid kits for themselves).

That’s all for the underground level, we are against spoiling everything before the release, so you probably won’t get more details before the release. On a side note, a few people asked us if we could give an approximative completion percentage for each level, so here it is:

  • Forest: 90%
    What’s left: soundscapes, items/weapons tweaking, nav tweaking
  • Manor: 60%
    What’s left: exterior, sounds, event, items/weapons, nav
  • Underground: 95%
    What’s left: soundscapes
  • Lumberyard: 50%
    What’s left: detailling, event, sounds, items/weapons, nav
  • Lakeside: 15%
    What’s left: everything except prototyping and ambient

Stay tuned for more developer banter until the release.


Unfortunate SDK Accident (fixed)

Posted by Nicolas in Lamentation

Tags: , ,

Believe me, we’d really like to add some news on this front page, but I got an unfortunate accident with my Source SDK. Today, without any warning, it just stopped working. When opening up the Source SDK Launcher, there’s nothing I can do anymore. It opens correctly, but I can’t click anymore on the tools. If I try to double-click on Hammer Editor, Model Viewer or Face Poser, the SDK Launcher just stops itself without any error message and without launching the corresponding application.

This is not the first time the Source SDK stops working… but this is the first time it does not display any error message. I tried the usual stuff: Refresh SDK Content, Reset Game Configurations, Defragment Cache Files, Verify Integrity of Tool Cache, Restart Steam, Reboot Windows, Delete the ClientRegistry.blob, uninstall and reinstall the Source SDK GCFs, delete everything SDK-related in Steam and reinstall everything from scratch… I even deleted the whole Valve preferences from the registry. So far no change.

I used the SDK for a few hours and it stopped working when I tried to relaunch Hammer using a different game configuration. The only thing I did before it stopped working is install the Dawn of War II Demo (but I doubt this was related, I uninstalled it just to be sure). There was also a Steam update released at the same time… I really don’t know what to do, if some of you already faced the same problem someday and know what to do, please post in the comments or send an email to, I really need it to finish the fifth map of the campaign…

Edit April 18:
I just entirely uninstalled Steam and reinstalled it only with Source SDK to witness that it doesn’t change anything. I’m now completely stuck.

Edit April 19:
Mokay, I uninstalled Steam again, trashed ALL the GCFs (sigh), deleted the whole Valve registry key, cleaned the computer with TuneUp, and installed everything back from scratch (40 GB of GCFs to download, sigh) and things seems to be working again. Thanks to the people who tried to help there and via e-mail, much appreciated.


Early Left 4 Dead SDK access?

Posted by Nicolas in Development

Tags: ,

Yesterday, we learnt that some people managed to get their hands on some private-exclusive-early access to the Left 4 Dead SDK. Which means a few things :

  1. First, that there is a SDK. That’s not as bad as some people thought after all. Even if it’s five months late, it’s still better than never.
  2. Second, that Valve is testing it. Therefore, we can assume that they got it right this time. Hopefully, when the “new” SDK comes out, it shouldn’t screw everything during several weeks this time. But seriously, we’re not really this confident, and chose to prevent the automatic SDK update in Steam anyway.
  3. Third, we know that someone at Valve’s headquarters is reading this blog, Google Analytics is tracking you! What are you waiting for to offer us an early access to this SDK? Come on! Mail us at, dont be shy! :P

Anyway, since I developed a little tool to handle the custom content, sort it between Left 4 Dead content and external stuff and embed it automatically in the map files, it’s not much of a problem anymore. BUT STILL, we’d really like to see the new functionalities, if any.