S&T | Artificial Intelligence in Video Games : Conceptualize and Conquer
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S&T | Artificial Intelligence in Video Games : Conceptualize and Conquer

By Firas Safadi, Raphael Fonteneau, and Damien Ernst 
Universite de Li ´ ege,  Belgium

S&T | Artificial Intelligence in Video Games : Conceptualize and Conquer

Since video games, despite their apparent diversity, share concepts extensively, creating Artificial Intelligence (AI) that operates solely on concepts should allow developers to use it for multiple games. This raises an important question however, namely, that of the availability of a conceptual interpretation of video games. In reality, for AI to handle conceptual objects, it must have access to a conceptual view of game data during runtime.

When humans play a video game, they use their faculty of abstraction to detect analogies between the game and others they have played in the past. Abstraction in this context can be seen as a process of discarding details and extracting features from raw data. By recalling previous instances of the same conceptual case, the experience acquired from the other games is generalized and transformed into a conceptual policy (i.e., conceptualized). For example, a player could have learned in a role-playing game (RPG) to use ranged attacks on an enemy while staying out of its reach. This behavior is known as kiting. Later, in a real-time strategy (RTS) game, that player may be faced with the same conceptual situation with a ranged unit and an enemy. If, at that time, the concept of kiting is not clearly established in the player’s mind, they may remember the experience acquired in the RPG and realize that they are facing a similar situation: control over an entity with a ranged attack and the ability to move and the presence of an enemy. The player will thereby conceptualize the technique learned in the RPG and attempt to apply it in the RTS game. On the other hand, if the player is familiar with the concept of kiting, a simple abstraction of the situation will lead to the retrieval of the conceptual policy associated with it, without requiring the recall of previous instances and associated experiences and their conceptualization.

Note that kiting can be defined using only concepts, such as distance, attack range and movement. Distance can have several distinct interpretations, for example yards, tiles or hops. Attack range can be a spell range, a firearm range or a gravity range. Walking, driving and tele-porting are all different forms of movement. Kiting itself being a concept, it is clear that concepts can be used to define other concepts. In fact, in order to define conceptual policies, different types of concepts are necessary, such as objects, relationships, conditions and actions. Weapon, enmity, mobility (The condition of being mobile.) and hiding are all examples of concepts.

According to the process shown in Figure 1, conceptual AI, that is AI which operates entirely on concepts, could be used in video games under the premise that three requirements are met. These would be:

(1) the ability to translate game states into conceptual states,
(2) the ability to translate conceptual actions into game actions, 
(3) and the ability to define conceptual policies. (A conceptual policy maps conceptual states to conceptual actions.)

Figure 1: Possible process of human decision making in a video game using conceptual policies, as described above. If memory queries do not yield any results, a concrete policy is computed in real-time using other cognitive faculties such as logic or emotion.

Though the third requirement raises no immediate questions, the other two appear more problematic, as translating states and actions needs to be done in real-time and there currently exists no reliable replacement for the human faculty of abstraction. It follows from the latter assertion that this translation must be manually programmed at the time of development. This means that the game developer must have access to a library of concepts during development and write code to provide access at runtime to both conceptual views and conceptual controls of the game for the AI to work with. Using such a process, both the real-time availability and the quality conditions of the translation are satisfied.

Figure 2: Basic architecture of a video game using conceptual AI. The game maintains a conceptual view of its internal state. A conceptual view is the projection of a part of the game state into conceptual space. Based on this conceptual data, the AI controls an agent in the game by issuing conceptual commands, which the game translates back into game actions.

As is hinted in Figure 2, rather than translating game states into conceptual states discretely, it is easier to simply maintain a conceptual state in the conceptual data space (CDS). In other words, the conceptual state is synchronized with the game state. Every change in the game state, such as object creation, modification or destruction, is directly propagated to the conceptual state. Note that there is no dynamic whatsoever in the CDS. A change in the CDS can only be caused by a change on the game side, wherein the game engine lies.

Obviously, this design calls for a unified conceptual framework (CF). That is, different developers would use the same conceptual libraries. This would allow each of them to use any AI written using this unique framework. For example, a single AI could drive agents in different games featuring conceptually similar environments, such as a first-person shooter (FPS) arena. This is illustrated in Figure 3.

Figure 3: Using the same AI in multiple games. AI A can run in games A and B because both implement the conceptual interface A it requires. A conceptual interface is a set of conceptual views and controls.

From a responsibility standpoint, the design clearly distinguishes three actors:

(1)    the game developers, 
(2) the AI developers, 
(3) and the CF developers.

The responsibilities of game developers include deciding which AI they need and adding code to their game to maintain in the CDS the conceptual views required by the AI as well as implementing the conceptual control interfaces it uses to command game agents. Thus, game developers neither need to worry about designing AI nor conceptualizing games. Instead, they only need to establish the links between their particular interpretation of a concept and the concept itself.

On the opposite side, AI developers can write conceptual AI without worrying about any particular game. Using only conceptual elements, they define the behavior of all sorts of agents. They also need to specify the requirements for each AI in terms of conceptual views and controls

Finally, the role of CF developers is to extract concepts from games (i.e., conceptualize) and write libraries to create and interact with these concepts. This includes writing the interfaces used by game developers to create and maintain conceptual views and by AI developers to access these views and control agents.

Because the CF should be unique and is the central component with which both game developers and AI developers interact, it should be developed using an open-source and extensible model. This would allow experienced developers from different organizations and backgrounds to collaborate and quickly produce a rich and accessible framework. Incidentally, it would allow game developers to write their own AI while extending the framework with any missing concepts.

This article is an excerpt taken from a research paper, titled “Artificial Intelligence in Video Games: Towards a Unified Framework”  Hindawi Publishing Corporation International Journal of Computer Games Technology Volume 2015, Article ID 271296, 30 pages http://dx.doi.org/10.1155/2015/271296 

Download The Paper - LINK

Copyright © 2015 Firas Safadi et al. 
This is an open access article distributed under the Creative Commons Attribution License