Video Games as Soft Real-Time Simulations
Most two- and three-dimensional video games are examples of what computer scientists would call soft real-time interactive agent-based computer simulations. Let’s break this phrase down in order to better understand what it means. In most video games, some subset of the real world -or an imaginary world- is modeled mathematically so that it can be manipulated by a computer. The model is an approximation to and a simplification of reality (even if it’s an imaginary reality), because it is clearly impractical to include every detail down to the level of atoms or quarks. Hence, the mathematical model is a simulation of the real or imagined game world. Approximation and simplification are two of the game developer’s most powerful tools. When used skillfully, even a greatly simplified model can sometimes be almost indistinguishable from reality and a lot more fun.
An agent-based simulation is one in which a number of distinct entities known as “agents” interact. This fits the description of most three-dimensional computer games very well, where the agents are vehicles, characters, fireballs, power dots and so on. Given the agent-based nature of most games, it should come as no surprise that most games nowadays are implemented in an object-oriented, or at least loosely object-based, programming language.
What Is a Game Engine?
The term “game engine” arose in the mid-1990s in reference to first-person shooter (FPS) games like the insanely popular Doom by id Software. Doom was architected with a reasonably well-defined separation between its core software components (such as the three-dimensional graphics rendering system, the collision detection system or the audio system) and the art assets, game worlds and rules of play that comprised the player’s gaming experience. The value of this separation became evident as developers began licensing games and retooling them into new products by creating new art, world layouts, weapons, characters, vehicles and game rules with only minimal changes to the “engine” software. This marked the birth of the “mod community”-a group of individual gamers and small independent studios that built new games by modifying existing games, using free toolkits pro- vided by the original developers. Towards the end of the 1990s, some games like Quake III Arena and Unreal were designed with reuse and “modding” in mind. Engines were made highly customizable via scripting languages like id’s Quake C, and engine licensing began to be a viable secondary revenue stream for the developers who created them. Today, game developers can license a game engine and reuse significant portions of its key software components in order to build games. While this practice still involves considerable investment in custom software engineering, it can be much more economical than developing all of the core engine components in-house. The line between a game and its engine is often blurry.
Engine Differences Across Genres
Game engines are typically somewhat genre specific. An engine designed for a two-person fighting game in a boxing ring will be very different from a massively multiplayer online game (MMOG) engine or a first-person shooter (FPS) engine or a real-time strategy (RTS) engine. However, there is also a great deal of overlap-all 3D games, regardless of genre, require some form of low-level user input from the joypad, keyboard and/or mouse, some form of 3D mesh rendering, some form of heads-up display (HUD) including text rendering in a variety of fonts, a powerful audio system, and the list goes on. So while the Unreal Engine, for example, was designed for first-person shooter games, it has been used successfully to construct games in a number of other genres as well, including simulator games.
