E3 2008: Left4Dead Interview. New Graphics, Weapons, and Steam Achievement Details


Face it, pirates and ninjas are out and zombies are in. And we have no doubt that one of our most high-anticipated games of this year is Left4Dead, Valve’s post-apocalyptic survival horror shooter. Our initial playtest sent chills down our spine when we first saw it at last year’s Showdown LAN, and the game looked much more refined and polished when we played it at this year’s E3. A revamped visual style and new character designs suit the cinematic direction -- the levels looked grittier and the zombies were definitely more terrifying (if that’s even possible). We spoke with Michael Booth, the designer of Left4Dead, to find out what other changes have been made to the game since Valve bought up his development team.

Maximum PC: Tell us a little about Left4Dead, assuming we've never played it before.

Michael Booth, Designer: So the main thing with Left4Dead is, in a nut shell, it’s you and your friends surviving the zombie apocalypse. But the key thing that we’re pushing for with this game that differentiates it from any other game like this is the level of cooperation that’s required. This is really a cooperative game. With other cooperative games you may be able to play the same game together [with friends], but you kind of do your own thing. In this game you have to stay together, work together, and watch each other’s back. Because if you run off by yourself, you’re going to die.

MPC: So we just spent some time playing the game and we noticed a couple of things right off the bat: zombies running up to people, us punching them off, people getting knocked down, zombies are piling on them and then we have to punch them off and then help our teammates back up. Stuff like that -- healing other people sharing ammo.

MB: Right. At the most fundamental level, there are just too many zombies that you can’t handle them yourself right. But then beyond that we have explicit attacks like the Hunter’s pounce. If he pounces on you, you are helpless -- you’re done and will die unless a friend comes and saves you. The Smoker’s tongue is the same way. He pulls you way out of position but once he gets you he’s going to squeeze you until you die.

MPC : This is the thing that comes and grabs you from above and sucks you up into the air.

MB : Exactly. And with the Boomer you know if he hits you with his vomit then you’re tagged. All the zombies will be coming after you so your friends need to help. The Tank is another good example where if everyone stays calm and focuses fire on it you’ll probably be ok. But if the team panics and someone breaks and runs, the team spreads apart you’re in big trouble. And then of course there’s reviving people when their health reaches zero.  I can guarantee you that if you don’t do those things the team is not going to make it.

MPC : So one of the things that Left4Dead does that is really kind of unique is the really dynamic difficulty system. Can you explain a little bit about that?

MB : Dynamic difficulty isn’t exactly the right term. It’s a dynamic drama pacing system so it doesn’t nerf the game to bring it down to someone’s level so much as it really makes sure that you have an exciting experience. It’ss very easy for us in this game to give you a very intense experience.

MPC : You just keep throwing zombies non stop and…

MB : Right. So what the “AI Director” is doing in that case is it’s watching for cases where the team is just getting pounded on and then it’ll ramp things down a bit, to make sure there’s a gap a pacing.
MPC: So you watch statistics like health, the number of zombies the survivors have killed, and how much ammo they have, and then make decisions?

MB : Exactly.

MPC : What are the exact variables that the Director monitors?

MB : Well I can’t give you a full set of them. But it’s things like you just mentioned. It’s things like whether you’ve been hit recently, how often have you been hit, how many zombies do you see, how many zombies are running at you, and how many zombies you’ve killed recently.

MPC : All the way down to your level of accuracy or not so much?

MB : Not so much accuracy. It checks to see when you killed that zombie if he was way out in the distance wandering and not so much a threat or if he was in your face and hitting you -- that’s a little more intense. So its metrics like that. The Director’s doing that to make sure that there’s high peaks and valleys because if they’re all valleys you quit because it’s boring and if it’s all peaks you get stressed out and you quit anyway. So we want you to have the same kind of excitement as a rollercoaster ride. And of course the Director makes sure everything is procedural so you can never predict when or where the zombies are coming from.

MPC : Cool. What’s this we hear about the game having two modes?

MB : We tried for a long time to sort of have this holistic mode that did everything. You could play as a survivor or you can play as the infected and it all just worked. But we basically found that we were reaching diminishing returns and we could serve the game better by splitting it into two modes. It’s essentially PVP and PVE. There’s pure co-op mode where we could focus on the survivor’s experience against the AI controlled infected to make sure that they have the best dramatic experience that they can have. And then we have the Versus mode which is survivors versus four player-controlled zombies and you can take over the Tank, Boomer, Hunter and Smoker. So the basic thing is that when you join Versus mode you’re signing up for a tough experience.

MPC : You know what’s coming.

MB : Yeah. If I’m going to play Versus mode I know it’s going to be rough but I also know and its going to be awesome. As opposed to if I just want to play a co-op game with my friends and kill zombies and you know you’ll be able to avoid jerks.

MPC : So it’s purely a user preference and difficulty expectations or is the Director algorithm any different?

MB : The biggest thing is user expectation so you know what you’re signing up for. At the same time we’re able to relax some of the really tough constraints like Boss Infected spawn times and things like that that were really difficult before.

MPC : When we join a Versus server and two of our friends sign up, are we playing as a group or does it keep shuffling people around? Is there some sort of mechanism to control how often I’m a zombie and how often I’m a survivor?

MB : Some of that is still in flux but we are spending a lot of effort on matchmaking so it’s really easy to find and connect with your friends. The way that we’ve been doing the Versus mode is that the four zombies win by eating the four survivors., who win by escaping. After each round, the teams just swap and either you play again on that campaign or you go to the next campaign. It’s a total revenge thing.

MPC : So its attack versus defend.

MB : Yeah.

MPC : In your playtests do you find that one side wins more frequently?

MB : That’s where it gets interesting. I’m confident that we’ve got the game mechanics reasonably well-balanced so it comes down to the skills of the players. Just like in Counter-Strike, if you have a clan playing on the T’s and a bunch of random people from the net playing on CT’s, they’re going to get owned.

MPC : What’s the kind of play time to get through a level. I know it varies wildly depending on skill levels but are we looking at something like 30 minutes or an hour? Is it more like a WoW raid or is it like a pickup game of TF2?

MB : I would say more a WoW raid. If the team knows what they’re doing they can get through a campaign in about 45 min but that varies wildly. I mean we’ve had like company-wide play tests where some people took 2.5 to 3 hours, because if the survivors all die they roll back in time to the safe house checkpoint and at the (health and ammo) state they were at too. Some people had to retry sections of the map, especially the finale, since it can take some folks a few times to get through.

But that said, we also have AI controlled survivor bots as well so you can play alone and the rest of your teammates will be controlled by the AI. The nice thing about that is friends can drop in or out at any time and be replaced by a bot (or replace one).

MPC : Will the game run on dedicated servers or will it be an Xbox style local host? What do we need to have set up to get the best experience for us and 3 to 7 of our friends?

MB : All I can say right now is we’re investigating some really cool stuff with servers and hosting. Making it easy is a primary focus. Making it clear for you to jump in and play with the optimal experience right out of the box.

MPC : Because we might not necessarily be playing a pick-up game TF2 where you can jump into any server and have fun by ourselves.  We want to play with our friends and not necessarily want to pay 10 bucks or 20 bucks a month for an 8-person server.

MB : Yes definitely. You should not have to pay 8 or 10 bucks a month to play on a server to have a good experience.

MPC : We saw at the end of a mission there are rankings and you get feedback from the game. Can you talk about that and maybe a little bit about the Steam achievements?

MB : Yeah well we’re going to have a full set of achievements for both the PC and the Xbox 360. If you look at what TF2 is doing with their achievements you’ll have a pretty good idea at the kind of things we’re going to do for Left4Dead.

MPC : Any hints as to what the achievements might award?

MB : Well I will say that we are definitely going to focus more on altruistic and teamwork sort of achievements so you’d be recognized for the kinds of things we want you to be doing in the game. But there’s also going to be some other ones that are tough to do. I can guarantee you there’s going to be an achievement of starting and escaping a scenario without getting hit by an infected.

MPC : So that’s an achievement you might have to farm.

MB : It’s going to be tough, especially since we also have dynamic levels which are kind of unique for a multiplayer game. We’re figuring that out how this is going to play into the achievement system.

The feedback system we originally had was this really deep system of awards and merits and all this other stuff. There was a lot of data there but through play testing we found that people just didn’t care about that data. It was kind of information overload, and more importantly, it was kind of obscuring the salient things we really wanted people to notice.

MPC : Like if you shot friend in the face 20 times.

MB : Yeah so we want to highlight the good things and we want to encourage teamplay.  But, for example, instead of a friendly fire demerit the game will mention things like least damage to friends and that’ll be a ranking. So you can look at yourself and if you’re at the bottom of the list, that’s bad.

MPC : Yeah we wouldn’t want you on our team again.

MB : Right and it rotates through those rankings. It tries to pick a handful of the most interesting things that happened to show you. Like most headshots.

MPC : Kind of like at the end of a Rock Band round.

MB : Exactly. In fact, the game does rate your team with 5 stars as well. In essence what we’re trying to do is give the team valuable feedback and we try to boil it down to “you did really well,” “you did ok,” or “you should try different tactics next time.”

: Where does the difficulty kind of cap out? If we sit down with our mom and grandmother then obviously it’s going come in pretty easy. What happens when I sit down with guys who are at the top of the world? Are we just going to get infinite spawn of zombies?

MB : The fundamental thing that’s going to drive that in the coop mode is the difficulty setting you choose. There is sort of a bottom difficulty, and the director can only compensate so much. But on the top end so we have Normal, which is basically the introductory experience. We have Hard which is just a good solid experience for seasoned players. There’s also Expert difficulty which is for pretty hardcore folks.

And then we have Impossible difficulty because it never fails. I remember Counter-Strike bots in particular. It didn’t matter how hard I made those bots I kept getting emails saying “dude they’re too easy.” So Impossible is the mode for bragging rights. And what basically changes between those modes is how much damage you take from the various attacks. So the mobs don’t necessarily get bigger.

MPC : How much more damage they deal as well?

MB : How much damage they deal to you fundamentally. Some of them do change, like the tank. The tank gets tougher. He can absorb more damage. But at the same time he can deal more damage. Like on Impossible he hits you once and you know you’re done.

MPC : Like in a real-world zombie scenario, when they have their arms on you that’s not going to end well.

MB : No, you know if I reached across the table and clocked you as hard as I could that would hurt a lot

MPC : Definitely. You’re much bigger than we are. We don’t want any of that.

MPC : How about the new weapons that you’re showing off today?

MB : So the biggest tweak is the pipe bomb. The pipe bomb before was very realistic, so it exploded like a real pipe bomb would. But in terms of gameplay mechanics, especially with this game, it wasn’t actually very functional. There are so many zombies that are coming at you from all directions that having one even fairly big explosion didn’t help in a lot of cases. So what we did is we McGuyvered it a bit. Now, there’s like a labeled battery strap on the bomb with a beeper and the beeper sound just drives the zombies nuts. They have to chase the sound. So you can pull out the pipe bomb and set it off and it starts beeping faster and faster and all the zombies in the area chase down the pipe bomb like a dog chasing a bone. They kick it around and after about six seconds the beeper keeps getting faster until it explodes. But of course it’s completely surrounded by zombies at that point. So it becomes very tactically interesting. You can use it to get out of trouble. Like if one guy is dead and two are incapacitated and you’re going over to heal them, there’s probably a huge hoard coming at you. But if you have a pipe bomb you can use it and throw it far away and it’ll just basically absorb that hoard and you get a “Get out of jail free” card.

MPC : Can one of the player-controlled Boss infected kick the bomb back at you to send the hoard in your direction?

MB : We’re still experimenting with exactly how the Boss infected can react to the pipe bomb.

: And then the other big change we’ve seen today is the look. All of the characters have been redesigned and the game has new post-processing effects. Can you talk about that?

MB : As you know at the first of the year valve acquired Turtle Rock studios so now we’re Valve South and the biggest thing that the acquisition brought is just a ton of new resources. A lot of our game design assumptions changed. Before this time there were basically 12 of us building this game and we were leveraging as much as we realistically could using props that we had built for Counter-Strike. But now we have all this additional talent with Valve as a whole. Everyone sat back and said ‘This game is really fun. People really dig this game. Lets give this game its own look.’

What happened was a re-evaluation of our development and a whole bunch of effort going into giving the game its own unique art style. We are able to do things that we couldn’t do before like changing the low-level Source Engine assets because we had our hands full in just making the game itself. But now, we’re Valve! So now we have much more interesting shadows and flash lights and we have the vignette-style post-processing and the color correction.

MPC : So what is the “look” that you’re going for?

MB : What we’re trying to do is make you feel like you’re in a horror movie.  It’s a very cinematic feeling. Something that we’ve noticed just with the game in general is that people tend to like just to watch; they like to be spectators. Because it’s kind of like watching that horror movie where you want to shout ‘No, don’t, No! don’t go in there!’ We’ve really pushed for that in the vocalization – the way survivors talk to each other. We also wanted to make it look as filmic looking as possible.

It’s a challenge because there’s this single-player narrative element and structure, but it’s also a multiplayer game that is meant to be played over and over again.

MPC : Any details about the actual story behind the zombie infection? Is that something that will be revealed through the acts?

MB : We’re trying some experimental things with the story but we’re keeping it vague right now. The idea is as you play the game more and more the kind of things the survivors say will give you  little hints and tidbits of the story. So you may have played the game for a long time and then Bill says something off hand that you’ve never heard before. We have plans in the future to continue to add to this world a lot.

MPC : Will the game be moddable?

MB : That will be interesting to see how that works out. In some ways the game is really moddable in that you can make a map and you won’t have to populate it because the director does that for you. You basically generate what we call a navigation mesh and you decorate a few areas indicating where the players start, where the safe room is located, and where the finale will take place. The Director will go through and populate it all for you. And the director is there and available to be messed with but of course all it knows is how to make a zombie game so it’s not a completely malleable piece of AI that could say make My Pretty Pony or something.

MPC : My Pretty Pony would be pretty weird.

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