In The Last of Us, players control Joel who has seen the world fall apart after a "fungapocalypse" while Ellie was born after modern civilization crumbled. Ellie is completely controlled by the computer, but The Last of Us won’t be one long escort mission. Ellie has been designed to react to situations and she will grow throughout the game. In this interview, Bruce Straley, Game Director, explains how Naughty Dog developed Ellie and the enemy artificial intelligence.
PART 1: On Blending Gameplay And Story Together In The Last Of Us
While players wonāt be able to directly control Ellie, what kind of choices will the AI get? Will she develop over time and learn new abilities?
Bruce Straley, Game Director: It would be a really flat story if only one of the charactersā arcs and moves and characterization developed. Ellie needs to move somewhere, too. Even though sheās capable from the beginning and comes from a dark world, and has done some things that show she can exist on her own. Sheās not used to the world and stuff Joel has to do to survive.
Youāre going to see her working with Joel to learn more and more capabilities. Like, she starts not knowing how to use a gun, maybe. But maybe she can pick up the gun and Joel can show her how to use the gun, and sheās going to acquire more and more of these abilities as she goes [through the game]. Sheāll gain more confidence with this as well.
Can you tell us how you developed the AI for Ellie? It seems like the AI is really competent for a partner character. With respect to gameplay, Ellie will develop as she grows as a āpersonā when Joel teaches her how to survive.
Itās interesting that those two things actually correlate. Just the same way Ellie is growing as a character, sheās becoming more and more trusting of Joel, [and] more capable. Sheās gaining skills like the usage of guns, scavenging the environment to help Joel and find things. She has a backpack, so she can store items.
About the AI, in Uncharted 2, one of the things we started on from the beginning of the project [was that] we knew we wanted to have these really big set-piece moments, like the moving train and we wanted a building to collapse. So, we wanted these moments, and from the very start of the project, we started working on the technology to allow us to do that. Well, the same happens for The Last of Us with the AI.
From the start of the game, we knew, to personalize these characters; to make sure they feel human and are they are making intelligent decisions; [that] theyāre not getting in the playerās way and it doesnāt feel like a babysitting mission, that was the first thing we took on. Weāve stripped down our AI, weāve torn it apart and reworked and reworked and reworked. Weāll continue to rework it.
The last thing we got done in Uncharted 2 tech was probably that moving foreground object stuff. The local and global pairing of objects to allow us to do the moving train, etcetera. Thatās the exact same thing thatās happening now. Weāre pushing and pushing and pushing AI, and itāll continue to evolve until the day we ship to make these characters real.
What about enemy AI? Are enemies going to be as reactive?
Again, weāre trying to make these feel like humans. So, this means the animations have to change. This means the behavior and decision making has to change. Thereās a lot of attention to detail. If I pull out a gun and shoot it, how is this group of people [here] going to react? They would probably scatter. And then if theyāre in survival mode, and they know I have stuff that they want, how many are going to group together and try to take me down?
Itās interesting to look at humanistic behavior. The scariest human is one backed into a corner. So, when I show my gun and when I start shooting, thatās going to cause a greatly different behavioral change [in enemies] than if I came out with a melee weapon. If thereās four guys vs. two guys, itās very different than if thereās only one guy by himself.
Weāve thought about all of these different scenarios and weāre modeling in all the different, most practical behavioral choices that a human, in a fun gameplay way, would make. So, itās still provocative. If thereās one guy and I have a gun, of course, heās going to go hide. That makes sense for that guy. Now, whether heās hiding to ambush me or hiding to get away from me, that might change as you go through the game, depending on the environment youāre in or the types of people that youāre around.
Can you tell us what your favorite unique weapon is? Whatās a really unusual weapon or item?
Well, smoke bombs are pretty interesting. We have something in the AI called ādynamic stealthā. Even though the enemies have seen you and started combat, once I run away and hide and Iāve broken the line of sight, theyāre gonna go searching for me. Then it turns back into, if you want to try sneaking around them, you can. This all happens dynamically. It doesnāt mean you have to keep fighting the whole time.
The smoke bomb is a great way to break this line of sight, and to go somewhere they donāt expect. The smoke bomb also creates a small concussive burst, so it allows you to rush them as well. Everything has multiple uses, so itās not as much the uniqueness of the weapon as it is all the different ways you see the AI can react to them. That brick, that I could use to bash you in the face, or throw it, or throw it at the environment.
How much of the world will we get to see? How far will Joel and Ellie get to travel? We saw they were looking for a car in the video, so how much of America will they get to see as they travel West?
We donāt have a vehicle sequenceāa driving sequenceāper se, but we have vehicles that you can procure. Billās the scene that you saw here at Comic-Con. Bill knows where he can get stuff to get a truck back up and running. So that truck is going to be used by Joel and Ellie to get further faster than if they were just going by foot. So, yeah, thereāll be different vehiclesādifferent means of transportationāthat youāll find throughout the journey.
The journey goes from the east coast to the west coast, so yeah, theyāll make it really far over the course of about a year.
We donāt need the vehicle to be drivable. We just need the vehicle to get the story purposes across. Youāre going to be able to see multiple environments quicker through this game if you get a vehicle and it gives Joel and Ellie a great goal to find one.
Since The Last of Us goes through a year, will you have time skips in between?
Yeah, weāre going to have season changes and time skips and collapsed time, etc. To, in a cinematic way, feel like youāre compressing this journey into a palpable timeframe.
Whatās your favorite point in the journey?
I probably canāt say it right now. It would be spoiling the game. To tell you the truth, the AI, the interactions with the enemies, and the choices that you have, whether Iāve crafted a Molotov or smoke bomb or some other inventory item, and used it, and seen how the enemies, the humans, react itāthatās special to me. And to see that these humans feel like theyāre making intelligent choices, thatās great.
And of course, thereās moments with Joel and Ellie that literally kind of bring a tear to my eye that happen throughout the story. Theyāre beautiful moments that I canāt tell you anything about, but Iām really excited to reveal at some point.
Published: Jul 23, 2012 01:55 pm