Jump to content
  • Advertisement

Game AI architecture for a RTS game

Recommended Posts

I am developing a RTS game involving robber and cops. I have designed a simple rule based AI system for the robber.

Goals of the robber AI:

  • Escape from the cops (robber should not get caught)
  • Conduct robbery

Current implementation:
The robber AI uses a rule based system to escape from the cops. I have written IF-THEN clauses to build the rule based AI system. The robber AI uses the knowledge of cops’ current positions.

Future requirements:

I am worried about the current architecture of this robber AI system. I read that rule based systems are inefficient and difficult to maintain. For the future,

  • I want the robber AI to use some power-ups (to escape)
  • The AI should consider the power-ups used by the cops before making decisions.
  • For conducting the robbery, the robber has to move to a specific location escaping from the cops.


  1. Is the current rule based AI system will flexible enough (and easy to maintain) to meet the future requirements?
  2. What can be better alternatives for the existing rule based system? (Like decision trees or state machines etc.)
  3. I read people suggesting that the rule based systems are difficult to debug. Can anyone explain why?

I would appreciate any thought/suggestions on this topic. Thank you.

Share this post

Link to post
Share on other sites

I think the main weakness of rule-based systems is a different one: They are fragile. There will be circumstances you have not considered, where following the rules looks dumb. You will have some rule that seems perfectly sensible, like "if you are hungry, go to the fridge", and then there will be a fire in the house and some idiot will go to the fridge because he was hungry.

My favorite architecture is a utility maximization paradigm, where you assign a utility value to each action the agent can perform (i.e. how happy it makes you), then pick the action for which this value is maximum. You still have rules, but they are expressed as terms in the utility function that indicate priorities, so staying in a burning house has a negative contribution to utility that is much larger than the positive contribution of going to the fridge when you have the munchies.


Share this post

Link to post
Share on other sites

Thank for your response Alvaro. Are talking about "Goal oriented AI"? The AI in which actions are taken to meet the immediate needs/goals. Will there be any advantage of using decisions trees instead of rule based system?

Share this post

Link to post
Share on other sites

That said, there are all sorts of benefits to using a decision tree (or more specifically, a behavior tree) than using a "rule based system". Since you seem very new to game AI (another reason this is a big challenge for you), read the article that Alvaro linked to (it's mine). That will give you an overview of the different types of architectures.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Advertisement
  • Advertisement
  • Popular Tags

  • Popular Now

  • Advertisement
  • Similar Content

    • By Shtabbbe
      I've had a game idea for a while, and I wanted to finally try to create it.
      Its a 2D open-world tile-based MMO. The concept is it is one world and multiplayer only, so everyone shares one world no matter region, platform, etc.
      I am having problems finding out what to use to start development, I tried Unity but saw some of the negatives and refrained and now im stuck, could anyone recommend some intermediate friendly 2D engines that can support what I am looking for? Preferably in languages that are or are somewhat like Java, C#, Python, JavaScript, Lua.
      Thanks for your help, im very new at this if you cant tell
    • By bellamabel2018
      cozzie Member 5035   Report post   Posted November 11, 2016 Hi all,
      I was reading Game engine architecture and with that, brushing up some coding theory.
      If I recall correct, polymorphism can help you for example to achieve the following:
      - create a parent class with a virtual function, that needs to implemented in child/ inherited classes
      - let's take a shape for example
      - I have a triangle and square class implementing their own Draw function, like declared a virtual function in the shape class
      Now my question is, how do I iterate through all child class objects?
      Simplified code:
      class Shape { public: unsigned int someVar; virtual void Draw(); }; class Triangle : public Shape { public: void Draw(); }; class Square : public Shape { public: void Draw(); }; // some program std::vector<Triangle> myTriangles; std::vector<Square> mySquares; // generate some triangles and squares for(size_t i=0;i<myTriangles.size();++i) myTriangles[i].Draw(); for(size_t j=0;j<mySquares.size();++j) mySquares[j].Draw(); I believe it should be possible to do the last 2 lines at once.
      How would I iterate through them at once, using the advantage that polymorphism should bring here?
    • By APKirito
      Hey guys,
       So I started making this 2D side-scrolling platformer a while back, and I just wanted to get some feedback on my current progress. I am making this game purely for entertainment/experience, and I have no intentions to monetize it. 
      Here is my general story that is yet to be implemented. The game starts off with a cut scene where the player, a teenage fox, is together with his family, and he is told to go sleep (who needs curfew) by his parents. The fox reacts bitterly and wishes his parents were to disappear. The fox then goes to sleep and wakes up the next day. However, everyone is gone. The fox then says "Wow I can do anything now and no one will care!!." He then picks up a rifle and walks out the door and then tutorial begins. (Link to tutorial video).
      After the tutorial, the player is brought into a randomly generated dungeon (Link to Dungeon Generation Demo) (Link to dungeon traversal video). In dungeons, the fox is tasked to extract catnip from randomly placed bong objects (don't do drugs kids). However, there are traps and enemies randomly scattered that the player needs to watch out for. Every dungeon has a kitty that the player can pick up. These kitties spawn Challenge Rooms which I will explain later. Every dungeon also has a store that accepts catnip as currency. The store sells rifle upgrades and guns. To buy a gun, the player needs a kitty to equip it to. Guns are used to kill enemies and bosses. To exit the dungeon, the player needs to find a house object which is placed on the bottom layer of the dungeon. The dungeon exploration part of the game was heavily inspired by Splunky. 
      When the player exits the dungeon, he goes back home. If he picked up a kitty while in a dungeon, a Challenge Portal will be in the room. The challenge portal teleports the player into a challenge room. In these challenge rooms, the player needs to dodge obstacles to get from the entrance to the exit. The player is rewarded with a lot of catnip if they reach the end without taking any damage. (Link to Challenge Room 1 video) (Link to Challenge Room 2 video) (Link to Challenge Room 3 video) <= Ranked in difficulty imo
      After a certain number of dungeon traversals, the fox is confronted with difficult boss fights, and this is where the story progresses. The fox starts to miss his parents. (Link to Boss Fight 1 video)
      I am thinking about making two alternative endings after the final boss fight. One is where the kitties the player picked up in the dungeons transform into the fox's parents. This shows that parents are always looking after you even when you don't know. This ending is triggered if the player picks up a minimum amount of kitties. The other ending is where the fox finds out that his parents were shot by hunters. This ending is triggered if the player picks up less than a minimum amount of kitties (lowkey just want the players to find kitties). If you read this far, you are a legend. Any feedback would be appreciated!! (story-wise, gameplay-wise, response to my video clips). THANKS

    • By Josheir
      I just looked at an interesting web browser game called Call of War 1942.  The idea is to keep playing you purchase gold with pay pal (interesting idea.)  It is pretty much pay right away.  The game is pretty impressive.  I was wondering if anyone could venture to tell me what programming language/languages are in use.  The content is great with a video right away that takes no time to load.  Than after a quick first win a professional pop-up declares your victory.  The screen has the choice of moving tanks, etc.  which happens right on the screen.  It really is a neat game so far, so how was it made? 
    • By CircleOfAwesome
      I'm not sure if you guys can help me, but I figured an entity-component OOP design would be in your realm of experience. I want some feedback on it.
      Lets suppose that I have the following (it's mostly pseudo code):
      A header type of file:
      public: Button (textLabel, position); private: GuiComponent label; GuiSystem gui; A implementation type of file:
      // Event hookers / hooks the events to the corresponding functions: label.Clicked(onClickObj); // label is actually a pre-existing object that I can hook an event to. Now whenever user clicks, onClickObj. executes. function Button(text, position){ label.Text = text; label.Color = "Blue"; label.Position = position; } function onClickDo(){ gui.ChangeColor(label,"Red"); // Passes in our label obj. that we have in private and set its color to red! gui.ChangeText(label, "Button was clicked!"); pause(2); gui.ChangeText(label, "Button"); // Changes text back to "Button." } This is basically a button that whenever is clicked, turns red and displays "Button was clicked!" which then turns back to "Button." It's just a simple example. Label is a pre-existing object and I can already manipulate it. I just want to place a whole ECS system on it.
      GuiSystem is a container or class blueprint full of methods that can be used on the GuiComponent such as flash color a.k.a makes the label flash random colors, etc.
      Then whenever I make something really custom like a server menu and I need buttons, all I need to do is create a custom class blueprint and inherit the Button class above. Then I replace/overwrite some of the functions and bam, I have a server menu. I would add more GuiComponent labels if needed too. Is this generally how gui-design-architecture works?
      To show you the example in detail for instance, lets say I want a server menu. I create class blueprint detailing all member functions a server menu would do e.g: AddServer() which adds server buttons, ConnectServer() which calls something like ServerSystem.Connect(server) and connects you to the server, etc. I would then override the click function onClickDo() to do the ConnectServer() type of function. Right?
      I know guis usually don't use ECS but I already have a gui class blueprint premade with all the properties and such and abilities to connect events. I'm just adding ECS ontop of it and putting functions in the GuiSystem container and when/if that container becomes full or bloated, I can split it off like GuiSystem.Effects.CreateEffect(label, effect) and etc.
      Do I have the idea of ECS on right? Thanks for reading!
  • Advertisement

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

Participate in the game development conversation and more when you create an account on GameDev.net!

Sign me up!