Previous Work


Based on personal experience and statistically irrelevant polls by Computer Gaming World magazine, the most popular turn-based strategy wargame was Sid Meier's Civilization series.

Screenshot of Sid Meier's Civilization II, published by Microprose, Inc.

The early Civilization games had a square grid and a camera with a fixed height angle and orientation. The user could pan in any direction, but camera zoom and rotation was not possible. The world was made up of two-dimensional images that were custom crafted for these camera limitations.

The game's emphasis was on developing and maintaining the infrastructure necessary for building a powerful empire. Players expanded their reach by building cities and linking them together with roads. Cities would only thrive if they were located near resources such as mines, forests, and fertile land for farms. If a city had enough access to resources, it would grow and have enough left over to build armies. Resource gathering was done invisibly by the computer - the player would select a spot on the map to mine and the player's resources would automatically start to increase. Even when a city was surrounded by enemy units, these invisible resource gatherers could go out and collect their goods.

Armies could be built and deployed, and each game piece was able to move a certain number of squares per turn, depending on the type of unit and the terrain. Each game piece had to represent multiple units since each square in the grid could only be occupied by one piece at a time. Players had to convince themselves that they weren't sending a single chariot into battle, but rather an entire chariot division. Also, the game grid's rigid position system imposed severe limitations on the types of strategies that could be employed. Another problem was that the scale of the game was completely meaningless. A city took up one grid space while a handful of peasants with pitchforks required the same amount of game space.

Multiplayer Civilization sessions required users to take turns at the same computer. Eventually a special version, called CivNet, allowed players at remote computers to play against each other via a direct modem connection.

The next game that impacted the game industry was Warcraft II. Warcraft II was the first RTS game to become popular, helping to define the genre. It was not just an RTS version of Civilization, it had to be something different.

Screenshot of Warcraft II, published by Blizzard Entertainment.

The most notable change from the Civilization world was that game pieces moved across the board in real-time. In order to support real-time movement, the rigid grid position system had to be thrown out. With the grid gone, more reasonable game object scales could be achieved. Rather than representing an entire city by a single grid square, each individual building could be represented in the game. With building placement opened up to the user, specific types of buildings could be made. A Barracks was required to build foot soldiers while an Ogre Pit was necessary to build Ogres. Along with specific building types, defensive structures like walls and guard towers could now be incorporated into the game.

Resource gathering was made more realistic by requiring the player to command special resource gathering units to chop down trees or mine for gold. A player's empire could crumble if all of his or her resource gatherers were idle or killed. Constructing buildings also required a special builder unit to walk to the construction site and start hammering until the building was complete.

By eliminating turn-based play, the only way to have multiplayer battles was to support modem and LAN play. This was the key feature to making Warcraft II a popular game. As a single-player game, Warcraft II was sufficiently entertaining, but as a multi-player game it was addicting. The types of strategies that could be employed seemed almost limitless and, because you were playing against human opponents, every game required new strategies. The games required creativity, guile, and a focused mind. You weren't just playing a game against someone, you were desperately trying to out-think and out-maneuver a cunning foe. Defeating a computer player could never be as satisfying as disposing of your next-door neighbor's poorly constructed defenses.

Compared to Civilization, Warcraft II was more focused on hand-to-hand combat. Units were animated so that players could actually see their Ogres swinging axes and opponents receiving the blows. The pace of the game was also significantly different. Without the turn-based system to slow down game play, games could become frenetic as players raced to claim resources and raise great armies.

However, Warcraft II did not completely discard the work of its predecessors. The user-interface was nearly identical to that of Civilization and the camera was still only able to pan around the 2D world.

After Warcraft II, the pace of new innovations in the RTS genre slowed. The emphasis focused on achieving more and more realism while maintaining a fun playing experience. Warcraft II's fantasy, cartoon-like atmosphere gave way to the modern-day military context in Command & Conquer.

Screenshot of Command & Conquer: Red Alert, published by Westwood Studios, Inc.

Game designers became increasingly interested in incorporating real-world military strategy into their games. One strategy that has been true since the days of Sun-Tzu's Art of War is to attack enemies from an elevated position. RTS games had not been able to capture the advantages of height because the games were 2D by nature. The first game to gain popularity that incorporated more than two dimensions was Cavedog Entertainment's Total Annihilation.

Screenshot of Total Annihilation, published by Cavedog Entertainment.

Total Annihilation featured a 3D rendering engine for the units, but the terrain still consisted of pre-rendered 2D images and the camera was still fixed at one orientation. Because of this limitation, the game still played like a 2D RTS game.

Presently, 3D graphics hardware is becoming somewhat standard in new computers and game designers can now make the leap into full 3D game worlds. One such example is Wargames by MGM Interactive.

Screenshot of Wargames, published by MGM Interactive Inc.

Another example is the winner of the Independent Games Festival, Fire and Darkness, which was written by seven college students over the past three years.

Screenshot of Fire and Darkness, published by Singularity Software.

These fully 3D games feature free-roaming cameras that can rotate and zoom in addition to panning. Fire and Darkness supports free camera height angles so that the user can view the world from above, from ground level, or anywhere in between. The 3D environments and free cameras create an immersive virtual world that feels very realistic when compared to 2D games like Command & Conquer. Further realism is achieved by incorporating inertia into the physics model of Fire and Darkness.

3D RTS games require another dose of innovation to make the games playable. The interface that has been present since Civilization is still apparent in the Wargames screenshot, but new interface questions emerge from the 3D world. How does the user control the camera now that it has so much added freedom? What happens when the camera is inadvertantly placed inside a 3D object such as a mountain range?

The task of managing interactions between game objects becomes more difficult as well. The Fire and Darkness demo is full of laser blasts that travel through small hills and then hit their targets. Apparently the programmers chose not to do full polygon-level collision detection with every object in the game. Where do developers draw the line in terms of what is and is not an acceptable 3D mistake?

Perhaps most challenging is that 3D games must run fast enough to be able to maintain an acceptable frame rate. These games pride themselves on their realism and interactivity, which demands a frame rate of at least 30 fps. At this rate the human eye cannot detect the change from one frame to the next.

From a technological perspective, a group of ambitious students fresh out of CS 217 could write a Civilization-style game in one semester. However, as you march down my brief history of computer war games, that group of students would quickly lose their ambition. The complexity of a 2D RTS game already puts the next game on the list, Warcraft II, out of the realm of possibility. Factor in the additional burden of a fully 3D world and the task would seem nearly insurmountable. Computer war games have become increasingly realistic by becoming complex programs that require a team of programmers to put together.


Back to the index

kdmukai@princeton.edu
Last updated: 05/02/99 11:25 PM

All files Copyright (C) 1999 Keith Mukai