Hi all! A month has passed since that story about F.E.A.R.. Since you liked it then, I’m dropping by again with new material. This time we’ll talk about S.T.A.L.K.E.R. and what I think is his most unique feature. Naturally, I touched on the topic of AI behavior. There’s nowhere without it.

Like last time, I wanted to understand the issue, went to the Internet and compiled it all into a video. This time it turned out to be much more difficult, because there is a lot of information there, but not much necessary information.

The cover is, of course, clickbait. It’s necessary on YouTube, so don’t pay attention.

According to SG rules, I am adding the text version. But, just like that time, I highly recommend watching the video version, because there are visual reinforcements to the words. Without this, it may be difficult to understand what is being said.

P. S. For those who already know the history of development – timings are in the description. But I went through a lot of sources so that the events were supported by the words of the developers, so I still advise you to look.

Welcome to a world where every time everything happens a little differently than the last time. This is the text (video clip) about the world of the zone. In fact, it turned out to be two texts (videos) in one, which I spent more than a month creating. About people who were able to promote a unique idea and about the implementation of this idea. But first things first.

Today I’ll tell you how the concept of the Shadow of Chernobyl appeared, why without the game F.E.A.R. there wouldn’t be the stalker we know, why did the developers have to cut down the life simulation and how does it work?. So sit down by the fire and… (ATTENTION! JOKE)

When a game falls into production hell and turns into a long-term construction project, it’s always bad. On the one hand, fans’ expectations are growing, on the other hand, the developers’ desire to meet them. As a result, it all inflates like a balloon and loudly bursts with release.

Cyberpunk 2077 will undoubtedly be considered a symbol of long-term gaming projects of the 20s. Announced many years ago, promised a lot, cut out half of what they promised, seasoned it with bugs and low performance, and sent it to press. Of course, later the game was fixed and it was even tolerable, but the sediment remained. And, as for me, it’s unlikely to become a cult. Despite all the advantages, for me there is nothing innovative, incredible or amazing. Well… there’s RTX there. But otherwise, there was no revolution. Once again, like an old man, I point out that there is no feature in the new game.

But with the main long-term construction from the 2000s, everything is a little different. Also long and painful development. The cost of bringing the product to market, as Sergei Grigorovich (Director of GSC) said, amounted to more than $5 million (0:51). A huge amount at that time. They also put a ton of content under the knife. Also a bloated marketing company with a lot of promises. And the same release, marred by tons of bugs and performance problems. But there is one important nuance. When I recorded footage for this video, I thought about playing for two or three hours. I ended up playing the game for three days. So I was once again convinced that the stalker –

UNIQUE GAME
Stalker "Shadow of Chernobyl" is a unique game. And the point is not even that everything is happening in the Exclusion Zone. Not that it had really interesting shooting, unlike other games. Or in unique quests. Or good graphics by those standards with dynamic lighting. These are all important gears that allowed the stalker to take a place in the hearts of fans. But without one of them Stalker would not have become a cult. And this is the A-Life simulation system. (Artificial Life)

Even if you knew nothing about it, then while playing stalker you probably caught yourself thinking that every stalker is going “somewhere”. Not just wandering around the map, but heading towards the goal. Sit by the fire, deal with bandits, have a snack at a bar, play the guitar or hunt for “flesh”, etc. d. And that’s how it was. Every NPC in the game, outside of story scenes, had a goal. And therefore, subconsciously, the player believed in what was happening. He felt that he was not being led by the hand. Don’t cheat. And life really goes on as usual.

When I started writing the text, it seemed to me that it would be easy to find information based on the stalker. In the post-Soviet space, the game has a great many fans, which means there will be an answer to any question, because? I was wrong. It was about A-life that there wasn’t much information and we had to try hard, delving into sources. We learned most by going through various interviews and lectures by Dmitry Yasenev, the leading programmer and creator of the A-life system, and Alexey Sytyanov, a game designer and screenwriter. And as for the development of the game… Many sources had to be checked several times, because there are a lot of gags and made-up facts on the Internet. Many pulled quotes from the book.AND.Z.N.b.: Supergame by Arthur Shigapov. But this is a work of art and you can’t take quotes from it. Yes, I was able to find confirmation that many developers helped him in writing the book and even the project manager, stalker TC – Andrei Prokhorov, but I still treat this source with skepticism. In one place they say one thing, and in another another. In case I have not found confirmation from the developers themselves, I will indicate this. But it’s almost impossible to restore the chronology of those years exactly by dates, and to convey the main idea of ​​this video, it’s not particularly necessary. And if you ask the developers how exactly the development was going at that time, the answer will most likely be a little different. Almost all sources, as always, will be in the description. (although there may not be enough space for everyone) Several more times I turned to modders to clarify how this or that feature of X-RAY works. For which I thank them very much.
It’s simply impossible to talk about the A-life system, because then it won’t be possible to explain with what difficulty Stalker got this very “trick”.
So let’s start with how exactly the life simulation system appeared in Stalker. Let’s make a short “history of the birth of the concept”.

HISTORY OF THE BIRTH OF THE GAME CONCEPT

“Roadside Picnic” was performed for the first time in 1998, long before Stalker. Andrey Prokhorov (Artist, who later became the head of the PM project) proposed it as the basis for the script for a new game by GSC, but then the choice fell on another story by another author and the Venom shooter appeared – Codename: Outbreak. "Picnic" was forgotten.

Concept one.

Initially, Stalker was a completely different game, rather… he wasn’t even a stalker. The project was called Oblivion Lost. In terms of genre, it was supposed to be a shooter with an emphasis on the plot, with a large number of scripted scenes, inspired by Half-Life. The setting was chosen, to put it mildly, like a mess. Stargate, robots, aliens, portals to other worlds, jungles, Aztecs, colonization of planets in the solar system… Everything mixed into one cocktail. In 2001, at the ECTS (European Computer Trade Show) exhibition, Ukrainian developers showed the world the X-RAY engine and announced Oblivion Lost. They promised a release in 2003 and a bunch of technical features. For example, realistic physics, 100 thousand polygons per frame, skeletal animation, dynamic lighting and much more. Already at the beginning of 2002, GSC assembled a demo version of the project and brought it to the Cannes Milia exhibition, held from February 4 to 8 in France. From a technical point of view, everything was fine there. Huge spaces, excellent graphics, no loading between parts of the location. But, as SHPILE magazine reported, the press and investors did not appreciate the technical genius of GSC, because the project turned out to be unremarkable compared to its competitors. Although there is also information to the contrary. On the Internet you can find a text excerpt from an interview with the then PR manager of the company Oleg Yavorsky, who claimed that it was then that they received offers from all major investors except Microsoft. Unfortunately, I couldn’t find the full interview.

But one way or another, Andrei Prokhorov (the Artist, who later became the head of the PM project), tried to change the project. According to him, he even told Grigorovich that the idea of ​​making a game about “space marines with the massive use of grenade launchers in wall-to-wall mode” on the X-RAY engine was trash.

Later in an interview, he said that “I did everything so that by the end of March 2002 Oblivion Lost (a game about space marines and star gates) became a postscript to the word STALKER, a game about the Zone where the chosen ones go, about Stalkers.»

Second concept.

The idea of ​​changing the setting towards the story “Roadside Picnic” began to emerge. According to various sources, this concept was proposed either by level designer Denis Volchenko, or Andrei Prokhorov himself, or both of them (Include either both). And around the same time, Oles Shishkovtsov (one of the creators of X-Ray, and later the leading programmer of TC) returned from Crimea (according to one information, he was returning from a gaming event, and according to another from his relatives), where he saw the unfinished Crimean Nuclear Power Plant.

The second concept was formed – change the setting to the “Picnic” of the Strugatsky brothers, move the scene of action to the Crimea to Kazantip, and associate the appearance of anomalies and other “picnic” things with the accident at the nuclear power plant. Thus, the most fantastic plot began to become more “realistic”. But the “on-rails” and “scripted” nature of the project has not gone away yet. The project name changes to S.T.A.L.K.E.R. Oblivion Lost, and the developers begin to gather in Crimea to collect materials for the game. In March 2002, Dmitry Yasenev (father of A-life) joined the team. Alexey Sytyanov (leading game designer and screenwriter) begins to promote the idea of ​​“simulation”.

Third concept.

And here, according to legend, Sergei Grigorovich and Andrei Prokhorov saw a program about Chernobyl on TV. Sergei suggests moving the scene to Chernobyl. Not everyone on the team was in favor, fearing that making a game at the scene of the disaster would be, at a minimum, unethical. But Grigorovich makes a decision and convinces the team. The decision, as we all know, is correct. (2:25) This was followed by a trip to the zone and what everyone already knows. However, the basic concept has not yet been approved.

Sytyanov and Yasenev together continue to convince the team that they cannot be like other projects, like Half-Life. We need to create a realistic, living and unscripted world. Sytyanov assured that making a cinematic shooter of the Half Life level is unrealistic with a team of beginners, and the stalker must have his own feature that will make their game unlike any other. The idea of ​​a living world was promoted for a very long time, the entire (or almost all) rest of the team was against this approach and wanted to make a competitor to Half-Life. There were even proposals to make rail and cramped levels. Again. The team was against the main feature of the Stalker series. What set it apart from its competitors.

Final concept.

By May 2002, it seems https://ninewincasino.uk/login/ that everyone can be convinced (1:57) that the game needs a living, unscripted world and the stalker becomes a stalker. A PR campaign begins, and Grigorovich, in an interview with a Eurogamer, even promises a cooperative game with collecting artifacts and a HUNT mode, in which players receive money for each kill of an enemy. (insert footage of the hunt here) They are already talking about the fact that there will be a complete simulation of life.

Although, of course, there is no trace of anything like this yet. Sytyanov later said that artificial intelligence only began to emerge in 2003, but certainly not in May 2002.
From now on, the concept of the game finally becomes “serious”. When asked what was the reason for the change in concept, Alexey answered: The change occurred when the ideology of the project changed. The reason is simple – we want to create a serious game that can touch players and leave a mark on their souls.

In 2003, THQ took the development under their publishing wing, and in 2004 they renamed the project S.T.A.L.K.E.R. Shadow of Chrnobyl. The game concept is finally fully approved. Or not?

Final concept?

In fact, despite the fact that the concept was approved back in May 2002, proposals to abandon the open world and switch to scripts were heard at least until 2004. Alexey Sytyanov was in such conflict with management that he was practically fired 7 times and was fired once for a week. But then the concept finally took hold and the Stalker project went to release at the established rate. There were three years left before release.

Rescue Stalker

Why was all this historical information needed?? All these names and dates? Because otherwise it would be unclear how “accidentally” everything went as it should. Of course, a lot of things were cut out. And the A-Life system itself has been simplified very, very much. A bunch of ideas were abandoned, dozens (if not hundreds) of promises were not kept. But the most important part of Stalker, his heart and his peculiarity, still made it to release. And it was Sytyanov and Yasenev who were able to preserve it and defend the need for A-life.

Alexey generally said that the most memorable thing about developing a game is pain and suffering. But all of them were steadfastly overcome and the life simulation system survived until release.

But now that you understand how difficult it was to preserve this idea, you can figure out what kind of system it is and how exactly it was implemented.

The idea of ​​the A-life system was simple, but difficult to implement: all characters and creatures should live their own lives and not depend on the player. That is, even when the GG is not near them or even wanders around another location, life in the zone should go on as usual. So that every passage, every journey in the Zone is unique. The idea is to make this very main character NOT the main character.

Therefore, the usual system, which can be seen in almost all open-world games, when all NPCs exist only around the player and then simply disappear, was not suitable. In stalker, each NPC had to be in the world constantly, even when he went to another location – he remained the same character and remembered all the information received earlier and continued to act according to his logic.

This was a very difficult task, given that Stalker consists of several locations that simply physically cannot be loaded at the same time, and this is several hundred (according to Sytyanov, thousands) units. Yes, and it was impossible to heavily load the processor and devote a lot to artificial intelligence. There was no such power or the game engine could not cope with it – it doesn’t matter. There was a division into levels and a limited productivity resource. It was necessary to work with this and come up with something.

This is how the division of the existence of characters into two modes appeared – offline and online.

OFFLINE and ONLINE

When the NPC is close to the player (around 150 meters), he is in the Online state. Uses equipment, builds detailed paths, “goes around this husk,” throws grenades, gets wounded, etc. d. Essentially, everything works the way we are all used to.

But as soon as the npc goes beyond this radius, he does not disappear, like in some GTA or Cyberpunk. It goes offline and stops calculating in detail. He does not build a detailed route, taking into account the terrain, he does not consider physics, visuals, animations – none of this. But he remains in the game world.

Sytyanov said that everything works like this: When leaving the online zone or moving to another location, the npc turns into numbers that move along a simplified route. Stalkers and monsters in the form of these numbers travel through the zone and when they collide, “dice are thrown” to calculate the situations “noticed or not noticed” “dispersed not dispersed” “who killed whom”, etc. d. But when the player comes to the place where he miscalculated, he will see the consequences of these collisions. Corpses of stalkers, monsters, etc. d. But at release this didn’t happen so often, because the game had a “cleaner” who removed garbage, corpses, etc. And often he cleaned everything up before the player got to the place. Just so the engine doesn’t crash.

By the way, sometimes, when an npc switched from offline to online, the game could sometimes freeze for a split second. Now you know why.

Movement\navigation

But for movement we also had to come up with a separate method, since the Zone is divided into several large levels.

For each level there is a navigation graph (can be characterized as a “navigator for bots”), which is used to move characters in ONLINE mode. It’s called a detailed graph and helps characters move around in detail. Consider obstacles, etc. d. In short, the squares used to calculate the AI ​​path.

But for each such graph, a less detailed version is created – a global graph, so that the characters move around the map offline. And it is already connected with the same global graphs of all other levels.

Here is an example of how this is used: if an ONLINE character for some reason wants to go to another level, he will first look at the global graph where he needs to go. Then he will check on a detailed graph of the level how he can “physically” get to the destination point and, if the point is in another location, he will reach the exit from the location and teleport to another, after which he will go OFFLINE mode. And so that the player does not see this, the NPC teleportation points are located further than the player’s teleportation point.

Life simulation.

So, initially, stalkers had to take quests from merchants. For example, to search for an artifact. After the npc found an artifact, he brought it to the merchant, sold it and received a new quest. This could even be the main quest. In the earliest versions of A-life, stalkers could actually complete the game before the player, that is, “reveal the secret of the zone”. By the way, the AI ​​itself still has the task of “revealing the secret of the zone,” but more on that later.
The stalkers were not tied to one location and roamed freely around the zone. For example, if two NPCs ran out of ammo, they ran after them and if the first one got there earlier, the second one started running away from him, got shot in the back and started bleeding. In short, there were many unique situations and the developers themselves watched them with great interest, not knowing what would happen.
But this simulation approach had problems. During the tests, it turned out that the average player simply will not understand what is happening and how to act. For example, he needs to take a quest from a stalker in a certain location. But he’s not there, because he was sucked out by a bloodsucker somewhere in a dungeon. Of course, you can run and look for his corpse all over the map, but few would agree to play such a game. The developers were afraid that people were not ready for this level of simulation. Therefore, it had to be “pressed” and mixed with scripted moments.

It was decided that npcs would receive quests not from merchants, but from smart terrains. For example, a stalker finds himself in some landscape, and he sends him to some place. He comes there, gets points – the quest is completed.

So in the stalker there appeared bases, solitary camps, gatherings around the fire, and so on. And the characters’ journey between them is the result of smart landscapes issuing tasks.

STORY QUESTS.

The plot points are more “classical”. This was made possible because the story areas were separated by "space restrictors". In this way, it was possible to avoid situations when the plot character, who was running about his plot affairs according to the script, was attacked by a swarm of olives, but he did not pay attention to them and died stupidly. Therefore, when the plot episode started, other characters didn’t particularly run there, and plot characters didn’t run away from there. But this did not greatly knock the player out of “faith in the world of the Zone,” because as soon as he completed the mission, all NPCs again obeyed the laws of the simulation. They could catch olives and throw lemons. HOW AI WORKSIf I talk in detail, then I need to make another video, so I’ll try to be brief (HA!) (although it is difficult):

In offline mode, everything is simple: if there is no task, select a task. If there is a task, move to this task and complete it. That’s all.
But in online mode it’s more difficult for characters. Their AI consists of three elements: Collection and processing of information Making decisions Low-level controllersReceiving and processing information
Characters have 3 types of receptors. Sight, hearing and touch (both olives and just the player). Having received information through them, he already clusters it into threats, enemies, objects, zones for increasing ratings, etc.

Decision Making.

First, finite state machines were used, then hierarchical finite state machines, then… in short, there were about 7 methods. And then Yasenev read an article by Jeff Orkin, who worked on AI in F.E.A.R. This is how the GOAP system came to Stalker, about which there was a previous video. Be sure to watch it if you don’t know what it is, otherwise it won’t be clear further.

Dmitry contacted Orkin, discussed some of the nuances and implemented the system into the game.

Unlike F.E.A.R., the planner is needed here not to build chains of actions, but simply to obtain the first action in this chain. This is convenient because the developers always knew what exactly a particular NPC was doing and why he was doing it. In the case of FSM, it would be necessary to go through hundreds of states and transitions between them and look for at what moment something broke. But the plan must not be empty, otherwise the bot will simply “break”. As you may recall, GOAP checks the relevance of plans by querying the plan’s preconditions and consequences. If one of the conditions changes, the plan is built anew. This is precisely what the “mystery of the zone” is for – an unattainable goal, for the fulfillment of which plans are constantly being made and rebuilt.

Each character in the game has ONE global goal: to reveal the secret of the Zone.

What exactly does this mean in the release version – I couldn’t dig it up. The modders told me that this is an “unsolvable problem”.
That is, the NPC asks “the problem is solved?"receives the answer "no", and now? no, but now? no, but now? no, but now? no and so on in circles.

To begin the “reveal the secret of the zone” action, the NPC must have met the prerequisites. He shouldn’t be hungry, shouldn’t be in battle, should have a weapon, etc. d. That is, you need to achieve these preconditions before proceeding to the goal. In one of his interviews, Yasenev said that if it turned out that all the preconditions were met, then, for example, the task appeared to “find some kind of artifact” that simply was not in the game. And the NPC will continue to try to complete this task, moving around locations, until he switches to another one again.

Properties (operators) were used to set the character’s behavior.

For the character they were something like this:

Am I aware of threats nearby?? true\false
Do I have any cartridges in my horn?? true\false
Do I have any assignments?? true\false
Am I in hiding? true\false

And there were about 70 such properties. And they, based on the answers to these questions, formed a plan to achieve the goal.

As I understand it, it worked something like this:
Do you see the enemy?? Yes. You can shoot? Yes. There are enough cartridges? No. Recharge. There are enough cartridges? Yes. Fire. You get there? No. Come closer. Fire. You get there? No. The player has been there for a long time? Yes. Throw a grenade.

But to make sure everything worked as it should, the game used a hierarchy of schedulers. That is, the operator himself could be the scheduler. In short, it turned out to be a kind of nesting doll, which I couldn’t really understand and I will be very glad if there is someone who explains this in the comments.

As in FEAR, if it was possible to interrupt an action instantly if the preconditions and consequences for which the plan was made did not coincide, then it was interrupted and a new plan was made (more precisely, the first point of the plan).

But monsters most often used continuous animations, so GOAP was not applied to them in PM, but hierarchical finite state machines (hierarchical FSM) began to be used.

By the way, this is also interesting. Different AI technology was used for Humans and Monsters. I think this also influenced the players’ perception of the world. For the better.

Low-level controllers.

This item was responsible for selecting the necessary animations, moving, playing all sorts of “come on, come on,” interactions with objects and other things. Everything was more or less standard here. In fact, this is not all that was involved in the A-Life system. But if you try to talk about everything, then even a few hours will not be enough, so I suggest moving on to the results.

Stalker: Shadow of Chernobyl is an amazing game. It was remade a thousand times, cut and shredded into pieces. She changed her concepts again and again. Overgrown with myths and legends.
And the system itself also turned out like this: remade, chopped, but unique. But, despite the fact that everything did not work at all as planned. And something didn’t work at all… after all, it worked! It seems to me that it was the A-life system that made stalker so interesting.

Despite the fact that it was further refined and brought closer to the original idea, it would be nice to see what GSC Game World would have turned out if the emphasis had remained on maximum simulation.

There are hundreds of mods on the Internet where craftsmen are trying to restore “THAT SAME STALKER”. But, as Alexey Sytyanov said, it will never exist.
The problem is that it’s different for everyone. For some, these are the developers’ promises about co-op. For some, a complete simulation of life. Someone dreamed of a huge seamless world, and someone chose one of the merged builds and is trying to bring it to a playable state, dreaming that he will be the one who will be able to bring to mind what the development team could not do back in the 2000s.

For me personally, “THE SAME STALKER” is the release version of the game from 2007, the disc with which I bought after school in electronics at a fresh place. I had an exciting adventure in a unique, living world. And now I also found out how it works and tried to tell you.

Before I finish, I want to ask you to write in the comments about the most memorable moment in stalker that happened to you. This could be a mod, the original Stalker or its sequels. And also ask what game or its feature you want to hear about next time?

And that’s all for today. If you liked the text (video), then the best gratitude would be a like, subscription and comment.