Semantic Game Worlds

Jassin Kessing

This page describes three research projects about using semantics in game worlds. Research was initially done as part of a M.Sc. project of 9 months, but was later continued with a 4-month project in order to extend the work and integrate everything into the Semantic Worlds framework of Tim Tutenel. In order to validate the research, we collaborated with re-lion during a Knowledge Transfer Project of 12 months.

Knowledge Transfer Project (2011)

Gained knowledge over the past few years was shared with re-lion, allowing them to expand Builder with powerful techniques to construct virtual worlds. Furthermore, tools of several research projects were merged into a single package, resulting in an extensive yet simple editor to specify semantics for entities in virtual environments.

Layout solving

Research and implementation regarding layout solving -automatic placement of objects in virtual spaces- has already been done by Tim Tutenel, making it easy to integrate into Builder.


Although semantics had been specified before, we have re-implemented it in a more consistent and solid way. Besides, a lot of new features were added, making it possible to specify entities in great detail. As semantics are a powerful means to improve object behavior and interaction, this greatly helped to cope all kinds of game scenarios. With semantics, one could think of attributes (the mass of an object, the nutrition value of food), states (a lamp can be on or off), a parent-child hierarchy (a side table is a table, which is a kind of furniture), matter (a tree is made of wood), and relationships (a monitor should be placed on a table).

All semantic information has been stored in an easily accessible database. Re-lion used this database to link semantic concepts to their concept of ‘building blocks’ in Builder. This allowed them to provide users search suggestions. For example, when a user searched for a cow, it would suggest to also place fields and tractors, as they also belong to a farm.


In order to specify semantics in an easy way, Entika was developed. Entika is a greatly improved version of the Library Editor of previous projects, and is updated to handle the new database structure and the new semantics. The idea remains the same: users can create classes that represent entities, such as tangible objects, spaces, and matter, and relate those to attributes, among others.

Semantics Engine

Although the Semantics Engine has not been used by re-lion due to time constraints, a lot of time has been spent to make sure all new semantics were handled correctly during runtime. This made it possible to see the behavior of entities during a game, and allowed the player to interact with them in more ways than usual.

In addition, a simple 2D test game was developed that shows the power of semantics. Different objects all show a different aspect of semantics. Examples are a car that can only drive with gasoline, gasoline that explodes when it gets in contact with fire, a fish that dies when not in water, a TV that can be turned on to provide more fun, ingredients that can be mixed to create soup which can be eaten to satisfy hunger, and two teleports that can be used to warp from one to the other.


The semantic concepts and parts of the implementation have been evaluated by several people of re-lion. This resulted in positive feedback and constructive critics to improve all work even more.


The Knowledge Transfer Project has been successful for both re-lion and Delft University of Technology. There has been a lot of progress in the specification of semantics for virtual environments, and the current work is a strong foundation for future projects regarding this topic. Re-lion, on the other hand, was able to incorporate some of the concepts, and improve Builder.


  • Paper: Kessing J., Tutenel T., and Bidarra R.: Designing semantic game worlds. In: Proceedings of PCG 2012 – workshop on Procedural Content Generation for Games, co-located with the Seventh International Conference on the Foundations of Digital Games. Rayleigh, NC (2012)

  • Paper: Kraayenbrink N., Kessing J., Tutenel T., de Haan G., Marson F., Musse S.R. and Bidarra R. Semantic crowds: reusable population for virtual worlds. TBP in: Proceedings of VS-GAMES 2012 – 4th International Conference on Games and Virtual Worlds for Serious Applications. Genoa, Italy (2012)



An overview of Entika


Entika Demo Game, see Videos below


Semantics can be applied to a wide range of objects. Download the videos below (or watch them on YouTube) for simple demos in a 2d environment.

Follow-Up Research Project (2010)

Semantic Game Worlds

To increase players’ immersion in game worlds, the world and all its residing entities should behave as one would reasonably expect. Nowadays, this is hardly the case, as game worlds miss semantics. In this research, we present a novel approach aimed at enriching game worlds with powerful semantics. This is done by introducing a semantic model for game worlds. In particular, the notion of services is proposed, by which virtual entities get to ‘know’ about their roles in the world, how they can affect other entities, and how others can interact with them. Furthermore, in order to demonstrate its wide capabilities, a framework is presented to specify semantics during game development, and to use it during runtime. Moreover, the research shows that this approach can easily be applied to existing game development domains, of which three are discussed: procedural content generation, particle systems, and agent systems. It is concluded that in a semantic game world, entities more easily acquire the behavior one expects, making them both visually and semantically convincing, and resulting in a game world with a deeper level of immersion and more dynamic gameplay opportunities.


  • Library Editor: specifying a ‘become hungry’ service for a human being.

  • Fire extinguisher: an extinguisher is used to kill a fire.

  • Can factory: cans are painted red, after which they are filled with coke.

  • Hungry agent: a hungry agent retrieves the key that is needed to unlock and open a chest with pies.



Specifying a service for a human in the Library Editor


Extinguishing a fire


Filling cans with coke


Going to the key that opens the chest

M.Sc. Project (2008/2009)

Services in Game Worlds: A Semantic Approach to Improve Object Interaction

To increase a player’s immersion in the game world, its objects should behave as one would reasonably expect. For this, it is now becoming increasingly clear that what game objects really miss is richer semantics, not eye-catching visuals. Current games’ lack of semantics is mostly due to the complexity of designing semantic objects. If game designers would have to design all semantics by themselves, and game programmers would have to implement the handling of these semantics, game development time would increase enormously.

The goal of this research was to improve the semantics of game objects (or more properly, entities) in virtual worlds, resulting in more and better object interaction in games. The research proposed a solution in the form of services, describing interaction possibilities between entities, and a structure that made it easier to specify them. An example of this is the service of a vending machine, which exchanges a coin supplied by a player for a soda. By introducing several components, such as classes, attributes and actions, a service was defined as the capacity of an entity to perform a particular action, possibly subject to some requirements. To incrementally specify and add services to game objects, a three-phased methodology was presented.

This approach has been implemented and validated by means of a prototype system, which enabled a simple and intuitive definition of services in an integrated environment. By using two different editors, services could be defined during the game development process. In turn, a semantics engine was charged with all service handling during a game itself.

It was concluded that if game designers are presented with the tools to easily add semantics to game objects, these objects become aware of their services, therefore facilitating more and better object interaction, resulting in a much deeper gameplay experience than in current games.


  • Paper: Kessing J., Tutenel T., and Bidarra R.: Services in Game Worlds: A Semantic Approach to Improve Object Interaction. In: Proceedings of the International Conference on Entertainment Computing, pp. 276-281. Paris (2009)

  • Paper Presentation: Services in Game Worlds: A Semantic Approach to Improve Object Interaction – 4th of September 2009

  • MSc Thesis: Services in Game Worlds: A Semantic Approach to Improve Object Interaction

  • MSc Thesis Presentation: Services in Game Worlds: A Semantic Approach to Improve Object Interaction – 5th of August 2009

  • Research Report: Services: Adding semantics to virtual game objects




The Library Editor


Unlocking a door with a key in the Tech Demo

This research is supported by the GATE project, funded by the Netherlands Organization for Scientific Research (NWO) and the Netherlands ICT Research and Innovation Authority (ICT Regie)