Bringing Washington D.C. to Life: The AI of Tom Clancy's The Division 2 | AI and Games

Key Takeaways

[Music] Tom Clancy's the division 2 introduces players to a war-torn Washington DC a battleground not just in the streets but the hearts and minds of its civilians as they fight to regain a semblance of order that is true to the values the city and its country are built upon it's been seven months since the dollar flew destroyed New York City and humanity is clawing back piece by piece presenting a new game design challenge for developers massive entertainment building an open-world game that is dynamic emergent and immersive keeping players on their toes and giving a sense of life to the world this leads to enemy factions wandering the open world looking for trouble friendly survivors patrolling near the captured settlements supply convoys that either need to be defended from enemies or raided for extra goodies or supply caches air dropping into DC resulting in all sorts of trouble I'm Tommy Thompson of AI in games and in my recent discussion with division twos lead AI programmer Phillip Dunston we discussed the process of building a system that allows for all these dynamic events to occur the problems that arise when bouncing these elements of systemic game design and the challenges faced as the established tools and systems migrated from the better cold of New York City to the sunny streets of Washington DC [Music] in New York you could you know you could stand on a street corner for a long period of time because the there was very few very little movement through the open worlds but in Washington if you stand on street corner for any length of time you know you are going to get engaged in in combat with a group of embassies moving through the world in the first division New York City is designated a quarantine zone it's become a tomb a monument to the devastating chemical attack just weeks prior and hence the number of non-combative AI is relatively minimal with pockets of scavenging enemies found throughout the open world but as the franchise moves from the chilling winter winds of the Hudson to the warmer summer breeze of the Potomac the team at massive wanted to increase the impact and spread a both friendly and enemy non player characters in the game map as part of the immersion we wanted to to give the NPC's you know a lot of purpose for being in in the world and some of this came through our design this was six or nine months after the outbreak Washington has you know gone through this yeah the phase where everything is you know is just madness and chaotic and now it's sort of starting to the civilians are starting to group together into settlements and the settlements have structure and the different the different factions all have their own you know strongholds and they have structure and we wanted to make that apparent not just through the story but through the players experience of seeing the NPC's you know you know interact and and move through the through the open world to achieve this the development team put together a living world activity system into the division to giving specific roles to non player characters as the ends of the world and ensuring that they perform a given task or duty so let's walk through how it all works and then some of the weird and interesting problems that emerged as the existing AI systems were being adapted to work within the Washington DC map we wanted Washington to feel much more alive we wanted to feel like that there was yeah there was always something happening that you could easily find a group of civilians or a group of hyenas and so it meant having you know the system that let you know NPCs you know move through the world the every system within the division - allows for a variety of different sequences to be executed each with their own objective throughout the execution of the sequence an MPC will assume a role or Duty within the world and as a same to a post with an asset space or region to operate within what that means is when you see a group of NPCs traveling through the open world be as a patrol team near a stronghold convoy moving between outposts or as a unit gathering resources from an area with food or water each NPC has a defined purpose but then the activity to complete as mentioned each NPC has a given role or duty to complete further assigned objective these are split into two types the special role which is given to one or more NPCs at the beginning of the action being executed or the unscripted role which is assigned in an ad-hoc fashion depending on what's happening in the world at that time a special role may be the NPC that's gathering the resources or carrying the boxes of supplies and the convoy while the unscripted roles are the guards providing overwatch either standing in a fixed position wandering on a patrol path or taking control of a mounted weapon but in order for NPCs to have a role they need to know not just what roles are available in a particular activity but where they should be doing it hence every activity has a set of posts attached to it each post is set by designers to identify what duties can be executed at that post the locations they should execute the duty from and the minimum number of NPCs that are required to satisfy a given you might need two or three NPCs to maintain overwatch or patrol a region there are different types of locations that can be attached to a post volumes for when they're gathering resources are guarding a region of the map Waypoint paths that are for patrol duties and fixed points such as a mounted weapon whenever the active objective changes the server attempts to assign NPCs already have an active duty to a new one in context of the current task but also prioritizes what posts should be assigned so mandatory posts that really help sell what these characters are doing are felt first with other unfulfilled posts being populated depending on the makeup of the remaining NPCs this all does a great job of reinforcing the performance theater of the game characters nowhere in the world they should be standing and what their job is at that point in time but what happens when an opposing faction appears or the player in fact and things start to kick off well each NPC post does actually dictate whether or not it should be maintained in combat and if so they'll continue to operate the behavior once the fighting starts after all there's no point standing around on that mounted gun if you're not going to use it plus any event an di decides to execute a specific behavior the behavior can dictate whether or not to release itself from a given post and get into the fight and this provides a nice continuity between passive and active activity so with this fairly extensive overhaul of the systems to facilitate the introduction of more dynamic and systemic AI throughout the open world there were still some issues the team had to address and much of that comes from the change of scenery the the openness of Washington was actually one of the biggest challenge we had coming from New York it's not just the fact that the streets in New York had sort of narrow and you know the high skyscrapers on both on both sides of the street hyper tall buildings but it's also that the amount of traffic you expect to see with broken-down cars and buses in New York meant that we had a lot of control over very long sight lines so that the combat tended to be you know quiet short range or mid range combat even in the open world and you get to Washington and one of the things we want to to show with Washington was you know we wanted to introduce a diversity of environment that wasn't necessarily there in New York we wanted wide boulevards tree-lined boulevards we wanted big you know grassy open spaces we wanted sort of university type you know queenstown type locations and that put a pressure not just on the performance as you mentioned we actually put quite a bit of pressure on our NPCs you know AMC behaviors and NPC systems we hadn't really you know we'd when we'd crowd the NPC's for division we had designed them around so short to medium distance combat and now something we had to deal with a lot longer certainty of sight ranges and what happens if you engage with the rusher sixty meters away typing are they just going to run towards you for the 15 seconds and then you know we didn't really want to increase our you know budgets for the number of NPCs that we had in the game because we thought that the number of mbc's were for working quite well in the division one we wanted to maintain the budgets at about the same level which meant that we had a problem then of what happens when you need to bring reinforcements into a fight because if you wait until you're almost you've almost killed all of a group of NPCs then by the time the reinforcements are spawns and come in the players been idle for for several seconds but spawning is a problem because you know it's difficult to find this place that's out of line of sight of the player if the players in a big open area so it put up quite a bit of pressure on our game design and our embassy behavior design as well as performance this resulted in a number of genes to have existing behaviors within the division AI is executed the first major change was that behaviors for archetypes were retooled such that they were more competent when fighting the player range with archetypes having additional tweaks to their behavior to compensate for the increased range this leads to some novel cases such as the black tusks Russia which has an assault drone so if the player is too far away it won't expose itself and instead rely on the drone to attack you a second major change to the systems was the NPCs would actively move around the open world in the original game NPCs would only move in very small groups and even this was kept within fairly tight ranges in the math now convoys and control point attack units are moving through a larger scale but they also have a direction and goal to complete this helps contextualize their position in the world and either results in you sneaking up on them and catching them off guard or accidentally bumping into them in the open world and creating a chaotic combat sequence this all has a knock-on effect on managing the AI behavior server-side as mentioned back in episode 35 of the main AI in game show AI decision-making happens server side and the client visualizes these decisions on PC or console this resulted in the game servers running low level simulations of where groups of NPCs are in the world and their objectives spawning them into the game when necessary and D spawning them should be complete a given task but not only is the number of active NPCs increasing and the tasks they're being assigned more complex there's also the issue of having them spread across a larger map Division two's map is pretty much on one-to-one reproduction of downtown Washington DC stretching from Roosevelt Island and Georgetown in the West with the National Mall leading up to the Capitol building in the east totaling at around four square miles of map it's an area that is around 30 percent larger than the original map of the division which was of course a scaled reproduction of midtown Manhattan this resulted in a more aggressive level of detailing or lured system compared to the first game the Lord ensures the AI behavior processing server-side is minimized if players are not near them as well as client-side rendering and animation operating at lower levels of fidelity if they're clearly farther away so this addresses the issues of map size and increasing the density of AI activity in the map but this didn't resolve all the problems emerged during development there were still legacy problems emerging from working on the first division namely that Manhattan has rather strict rules on how verticality is introduced to gameplay introduced challenges that were more than just the sight lines we have a lot more uneven terrain New York for instance was surprisingly flat not surprising if you've been there it is a very flat like Manhattan is a very flat area but Washington is definitely not flat and so that sort of again you know pushed the NPC's into an area that we hadn't had - instead of a whole new set of problems that we hadn't had to solve for for the division one yeah to be out of hand or you know NPCs fighting on slopes and and taking cover on slopes and doing you know climbing up onto trucks when the truck is on a slope that type of thing introduced a lot of sort of complexity there and then in addition Washington is just so much more colorful than the New York was so you know we had to you know a lot spend a lot of do a lot of work with our NPC design making sure that they going to be visible in the different sort of environments that you finds but with all these improvements it led to another issue the increased sight lines meant the AI could more readily engage the player as they walk down open boulevards but this leaves it open to a potential flaw in the enemy AI factions are much more likely to spot each other it's interesting that added sort of an extra level of difficulty we hadn't initially expected the NPC's because of the Long's the the open spaces continually see quite a long distance and we needed to control you know how to tweak how you know quickly they still saw the player will go into the player but we ran into then a problem of the embassies would very easily see each other moving through the world and so you know we have all the different factions mixed in together or moving through the world heading to a control points heading to resources and one stage during development you know this would all just break down because though they would just spot each other from you know 100 metres way get into a fight kill each other and yeah the player would either get there and they'd be fighting going on or what player would get there and there'd be like sort of you know one person left alive or something so we actually added to to dial down a lot of the what we call a detection system the like you know the the line-of-sight the how quickly the NPCs go into combat near those systems we had to dial those down when it was faction versus faction yeah sort of yeah interacting with each other in the open world because we needed more control over that simulation building open-world environments and games that feel lived in that field I Namek is an increasingly demanding challenge as the scope of games being built continues to grow the complexity of these characters and the ability to handle emergent gameplay as it happens in game has no clear solution but here we're seeing a natural iteration of the tools and systems from Tom Clancy's the division alongside many of the interesting challenges that they've faced along the way but there is still more to talk about on the AI of Tom Clancy's the division - next up I'm going to take a look at one the most powerful applications of artificial intelligence within the game that players never get a chance to see the testing bots whose job is to play the division during development the identified bugs are false within the game and I'll be telling you all about that in the next video thanks for watching this video on the AI of Tom Clancy's the division ii here on AI in games once again a special thanks to everyone at massive entertainment and ubisoft for the opportunity to work with them on this project and of course to all my crowdfunding supporters on patreon that make AI in games a reality have a good one folks I'll be back [Music]