Game Studies

How’s the Weather: Simulating Weather in Virtual Environments

Abstract

This article examines the role of weather in games, from both a gameplay and a wider ecological perspective. While weather is usually introduced merely as decoration, the author argues that more direct effects on gameplay would make games both more realistic and ecologically savvy. While some progress has been made in certain areas (wind blowing on the grass, rippling water, rain or storms affecting planes in flight simulators), there is still much room improvement and challenges for aspiring game developers and graphics artists.

Keywords: Weather, simulation, ecology, nature, environment, virtual worlds.

Introduction

When game developers, theorists, and critics discuss what features are most important when creating a realistic virtual world, they tend to focus on aesthetics and kinetics, or, in simpler terms, graphics and animation. Some aspects of “reality,” such as lighting effects and shadows, draw more attention than other, less dramatic, natural phenomena. The end result is that even the most realistic games offer a hodgepodge of realistic and very unrealistic effects; a patch of grass might flow in the wind, but a character standing in the midst of a terrible rainstorm won’t even get wet.

Perhaps the most significant of such “lapses” in videogames is convincing weather simulation. Although some games, particularly flight simulators, make bold attempts at depicting the weather and its effects on objects in the virtual world, most are content to either ignore it completely or offer it merely as ambience (i.e., rain or snowfall will be shown and heard but will otherwise have no physical effects on either the characters or the environment). What is interesting about this omission is the implications it has for real-life concerns like ecological awareness-how can games acknowledge the threat of global warming when game characters fail to take notice of a torrential downpour on their heads? Furthermore, and perhaps more significantly, failing to take notice of the weather-a natural phenomenon that has always eluded humanity’s power to control-is a way of denying the very central, dominant, and occasionally traumatic role that nature plays in our everyday lives. Men and women do not dictate the weather, and in so many ways, weather is the “real” imposing itself on their otherwise well-regulated lives. In short, realistic weather simulation may not only make a game more graphically realistic, but also more fundamentally “real” by offering a less predictable and thus more compelling simulation of human experience in the world of everydayness. Such a feat would only be possible in a videogame, where weather effects could be utterly significant yet completely unplanned, and not just “intended for effect,” as in films and stories that use weather.

Immersing players in believable, coherent virtual worlds-complete with their own physics and ecology-has remained an elusive, yet lucrative, goal for the game industry. Game makers often privilege their games’ innovations towards cinematic realism over all other factors. Even Steve Russell’s 1962 computer game Spacewar! featured the “expensive planetarium,” which “drew a realistic star field with all of the stars as seen from Earth down to magnitude 5” to add an extra touch of realism to its simulated rocket battles (Markowitz, 2001). Modern videogames like Doom III (id, 2005) and Half-Life II (Valve, 2004) make the realism of their three-dimensional virtual worlds a key selling point. These worlds are represented both graphically and aurally in multiple dimensions, and players must navigate them in a manner designed to simulate real-life. Though these games are not technically “virtual reality” simulators, they nevertheless allow players (through their avatars) to perceive virtual objects “under many angles, to manipulate them, and to feel their resistance;” features that Marie-Laure Ryan calls the “ultimate test of material existence” (Ryan, 2001, p. 71).

The ultimate goal of modern game development seems to be a state in which players would be unable to distinguish reality from virtuality-or at least to reach a point where the technology becomes “transparent,” causing us to “lose consciousness of the medium” and see “only the power of the story itself” (Murray, 1997, p. 26). Indeed, most industry leaders talk about graphics in ways strongly reminiscent of the ancient Greek model of mimesis, or art as the clever imitation of what it is not (and can never be). The belief of many game developers and critics is that this type of immersion is much easier in cases where the virtual reality is as much like our reality as possible; the more familiar everything feels, the less we notice the machinery behind the illusion. This is why one of the oldest goals of videogame technology has been to achieve photorealistic graphics that are much easier for players to “process” than the minimalist, abstract graphics of early videogames. In short, the more that game developers can make a game world feel like home, the easier it will be for players to forget they are playing a videogame. “The most immersive texts are […] often the most familiar ones,” writes Ryan (Ryan, 2001, p. 71). Lev Manovich offers the insight that game developers have striven not towards realism, but towards cinematic realism-since the public tends to perceive the visual experience offered by cinema as the most realistic medium. Of course, Manovich recognizes that new media has a key distinguishing feature: navigable space. Unfortunately, the game industry’s achievements in spatial realism has been consistent only in its lack of consistency; we now have the ability to render individual blades of grass blowing in the wind, but a realistic mud puddle still seems years away. Simulating any natural phenomena requires the development of proper algorithms, and these developments are funded according to the game industry’s priorities.

Given the game industry and the public’s obsession with cinematic and spatial realism, we might be surprised to learn that one of the most obvious and pervasive aspects of our daily lives, the weather, has been ignored or allowed to play only very minor roles in even the best-funded “A-List” videogames. Only recently have major videogame developers begun implementing weather simulation, even though many of their games are totally or partially set outdoors (Unreal Tournament 2004, for instance). Of course, one obvious reason for this omission is that videogame technology has only just become capable to do the intense calculations required to simulate weather. Weather is an astoundingly complex phenomenon-so much so that even the world’s foremost and best equipped meteorologists are only able to offer educated guesses about the likelihood of rain, sleet or snow. Furthermore, for effects like rain or snow to look and behave realistically, each rain drop and snowflake would have to be rendered separately as a set of polygons-quite a feat in an era when videogame developers are just mastering the art of making virtual grass behave believably. Nevertheless, a convincing representation of weather in a gameworld is sure to add considerable depth to the illusion. Realistically depicting weather events like thunderstorms, winds, and moving clouds would help support the idea of the game world as a living, dynamic navigable space-in other words, an ecosphere.

Weather simulation in videogames is intriguing for many reasons. From the perspective of a game developer, the key issues are how effectively modern game technology is able to render weather and how such a feature might affect gameplay. Modern games that already portray weather, like Myst IV (Cyan, 2004), may feature moving clouds, thunder, and occasional rainstorms, but these events have no direct effect on gameplay-the avatar moves about as easily as though it were bright and sunny, and water does not collect in puddles or drip off rooftops. From the ecocritic’s perspective, a relevant issue here is how developers striving to incorporate weather into their games are establishing tropes in terms of how weather should operate in virtual environments. Is rain merely an optical effect, or a tangible object that affects the avatar’s navigational abilities? Finally, weather simulation has interesting implications for makers and players of didactic games like Microsoft’s Flight Simulator 2004 (Microsoft Game Studios, 2003), whose critical success depends on how accurately they represent real-life scenarios. Weather simulation has played a very important role in flight simulation games because weather plays an obvious and important role in piloting an aircraft. Thus, most of the innovation in weather simulation has been from this niche of videogames.

This chapter explores how weather emerges within game development and game design implementation to argue that weather, as a trope for change, proves pivotal to game studies and ecocriticism in the representation of virtual environments. Weather presents one specific entry point into games and ecology, an entry point which brings together issues in engineering, game design, educational games, and the building of game worlds. In this chapter, I provide a general overview of weather in games to investigate its relevance to these and other issues.

Ecology and Gameworlds

Ryan defines four features of worlds: “connected set of objects and individuals; habitable environment; reasonably intelligible totality for external observers; field of activity for its members” (Ryan, 2001, p. 91). Of all of these features, a “habitable environment” seems like the greatest challenge-much more of a challenge than the simple “navigable space” described by Manovich. It is the “habitable” feature that distinguishes gameworlds from game surfaces, such as basketball courts, baseball diamonds, or chess boards. “Habitable environment” suggests a game world where the represented species would have available to them all of the resources they would require if they actually existed. They would be born, reproduce, grow old, and perish-the game of Life on a grand scale. For these habitable worlds to be believable, the player must have some conception that there is life in the virtual world beyond what is immediately visible on the screen. It must always be raining somewhere, even if the sky is clear and sunny when we look outside our window.

As the study of the relationship between organisms and their environment, ecology serves as a useful trope and a method for understanding gameworld development. The history of videogames reveals an almost linear trajectory of increasingly rich and integrated ecologies of gameworlds. In early arcade classics like Pac-Man, Q*Bert, and Super Mario Bros., the “organisms” have only a vague, abstract relationship to their environments, which generally serve only to delimit their movement. Jay David Bolter and Richard Grusin describe Pac-Man as being “completely opaque; there is nothing behind or beyond the interface” (Bolter and Grusin, 2000, p. 91). Gradually, game developers began offering more ecologically complex gameworlds. For instance, M.U.L.E. (Ozark Softscape, 1983) is an early colony simulation game that requires players to consider such ecological factors as the proximity of their farming plots to rivers, the placement of solar panels to gather sunlight, and the abundance of metals and minerals in mountainous regions. Weather events like cosmic storms occur randomly and have unpredictable effects on the players’ colonies. Later games like Maxis’ SimCity (1989) and Microprose's Civilization (1991) include more ecological elements which help shape gameplay and winning strategies. Finally, some games have appeared that are explicitly about ecology. Maxis’ SimEarth (1990) is perhaps the best known ecological game despite its disappointing sales performance.

As the above examples suggest, ecocritics and game designers may find an increasingly ripe source for analysis in the worlds constructed in videogames. To penetrate the intricate relationship between games and ecology-especially as games turn to ecological principles of growth, development, and change for gameworlds and game characters-I take a single aspect of the natural world as my point of entry: weather. Weather proves an excellent focus for several reasons. For one, the challenges of weather simulation are some of the greatest yet faced by game developers and hardware engineers. A game world with a coherent and realistic weather system would represent a grand achievement for videogame technology. A good look at the technological obstacles that must be overcome for developers to offer convincing weather in their games will provide insight into the current limitations affecting not only graphical representations but also the immersive potential of the medium.

Secondly, weather helps produce the illusion of a gameworld as a dynamic and lived environmental space, thereby providing a rich ecological area for inquiry. Cheryl Glotfelty, editor of The Ecocriticism Reader, defines ecocriticism as "the study of the relationship between literature and the physical environment" (Glotfelty, 1996, p. xvii). For Glotfelty, ecocriticism does for environmentalism what Marxist literary criticism does for Marxism; "Ecocriticism takes an earth-centered approach to literary studies" (Glotfelty, 1996, p. xviii). Whereas a Marxist critic might focus on the class relations in The Adventures of Huckleberry Finn, for instance, an ecocritic might wish to discuss Mark Twain's descriptions of the Mississippi River and its unique ecology. If we are willing to expand our understanding of "literature" to include non-printed creative works, we might engage in ecocritical "readings" of movies, television shows and computer games. Indeed, computer games pose an exceptionally rich opportunity for ecocriticism because so many games feature coherent virtual worlds, complete with their own coherent ecosystems. Given the ubiquity of videogames in American culture, the manner in which videogames present and construct the natural world and construct concepts of nature itself prove pivotal to both game development and real-world innovation with many games being used for simulations-as the Gulf War so painfully illustrated-and for education. The environment and weather present a number of eco-specific issues. For instance, is the player character's environment an enemy or obstacle that must be overcome? Or must it be exploited to win? Can videogames help encourage players to develop a more responsible attitude towards the world beyond their screens? However their use, videogames increasingly rely on eco-concepts for game design and game play.

Weather and the Technology of Immersion

Ecological tropes in videogames have largely been used to support the game world as a realistic environment; however, many games purposefully create environments with less depth so that they will be more transparent to players. Though some early adventure games like Steve Meretzsky’s Planetfall (Infocom, 1983) required players to secure food and drink for their avatar, many critics found such features “did not make for particularly interesting challenges” (Montfort, 2003, p. 149). Is weather one of those things that might potentially make a game more realistic at the expense of its recreational value? It seems worthwhile to look at some comparative examples from videogame history.

Earlier, I mentioned the “expensive planetarium” feature of Steve Russell's Spacewar! (1962). However, this feature was not part of Russell’s original version, which was originally designed to be played against a backdrop of random stars. Pete Sampson, one of Russell's fellow hackers at MIT, designed the "hack" called the "expensive planetarium" because he felt it would add much-needed realism to the otherwise abstract game. Sampson felt that a more accurate and thus more familiar star field would help other players suspend their disbelief and immerse themselves better in the game; to imagine themselves actually piloting the crudely drawn spaceships. As Brenda Laurel writes, "Real-world objects make representations more accessible, and hence more enjoyable, to a larger number of people" (Laurel, 1993, p. 125).

Sampson's hack is certainly noteworthy and significant to the history of game development-specifically, a development trajectory that is tied to technological innovation and highly skilled technology users. While the original Spacewar! ran only on expensive mainframes, many current ecological and weather simulation games can be accessed on home computers. Because games can now be accessed in homes and can process so many variables, games are excellent at presenting simulations to all players. In doing so, games may construct players’ perceptions of ecological concepts. For most players, the depth of the game world is directly tied to the game’s validity as a simulation. However, game design follows multiple design movements. What one designer considers essential is abandoned by another as a frivolous misuse of computing resources. Nolan Bushnell's Computer Space (1972), the first ever arcade game, was based on Spacewar!, but did not attempt to duplicate Sampson's hack-in fact, it even omitted the sun (Markowitz, 2005). Because games inconsistently use ecology and ecological elements, a single element like weather is used in conflicting ways in many games. Players familiar with how the weather works in one game world might find themselves challenged with a totally new weather system in the game’s sequel. In short, tropes of weather conditions are only now emerging in videogames, despite the industry’s long obsession with verisimilitude.

Indeed, it seems quite ironic (or perhaps apposite) that the word most often used to describe the player’s ability to lose herself in a virtual world is immersion, a word whose etymology can be traced back to “dipping or plunging into water or other liquid” (OED, “Immersion”). The irony stems from the fact that water is a notoriously difficult thing to represent realistically in virtual environments. When Jeffrey Katzenberg, producer of the animated film Shrek was asked about the greatest challenge faced by the computer graphics team, his response was “the pouring of milk into a glass” (Hiltzik and Pham, 2001, A1). This ante was upped for Shrek 2, in which the characters are at one point caught in a cloudburst. David Allen, the senior effects animator for Shrek 2, describes the complexity of the challenge in an article for Computer Graphics World:

Adding to the visual and technical complexity for Shrek 2 were organic settings with atmospherics such as rain. In one sequence, the characters are caught in a downpour. "We had geometry changing dynamically on characters' faces as water flowed on the surface," says senior effects animator David Allen. For rain, the team used a particle-driven simulation. "The simulation particles used the surface information so that they could drip water off the face," says Allen. "We generated blobbies from the particles in different thicknesses and rendered them with refractions" (Robertson, 2005).

To look realistic, the rain drops must be of the right shape, fall at the right speed and angle (affected by wind), refract light, and reflect whatever surfaces that pass between them and the viewer’s eye. Not only must the falling rain look realistic; it must act realistically: soaking whatever it falls upon. In Shrek 2, Donkey and Puss’s fur is shown to be affected by the rain: "We had to change both the direction and the specularity of the fur," says David Doepp, the film’s surface supervisor (qtd in Robertson, 2005). The team’s efforts in representing all these liquids and rain effects won them awards, but their task was much easier than the one facing the game industry. After all, Shrek 2 does not change with each playing the way a game must.

To portray rain and its effects as realistically as Shrek 2, a game must do all the necessary rendering and computations in real-time. This process would demand a large allocation of the computer or game console’s processing resources-resources that might be better spent performing other tasks. In short, adding believable weather effects would force a developer to subtract a great many other effects that might diminish other aspects of cinematic realism. Though we can point to several exceptions, the vast majority of titles take little to no consideration of the weather at all, even if the events depicted in the game occur outdoors during extreme weather conditions. The shirtless guerilla fighters in Konami's Contra (1988) move and fight the same way whether they are sloughing through a jungle or trudging through snow. The same is true for the very popular Donkey Kong Country (Rare, 1994). Even though Rare Ltd, the game's developer, included what was at the time a very impressive snow and rain effect on some levels, the fact that it was raining or snowing seemed to make no difference at all to the player's characters. By far the most common "weather" strategy in videogames has been to depict weather conditions, but not make them affect the way the game is played (the gameplay). We could compare the weather in these games to the faux drawers in cheap furniture; they might fool the eye, but lack depth, especially because games are played and so they present experiential spaces.

One obvious reason why rain and snow so seldom affect gameplay is the technical limitations of early systems like the Nintendo and Super Nintendo. In the case of Donkey Kong Country, when rain falls on the characters, we might expect them to visibly become wet, start shivering, or simply find a convenient shelter and remain under it until the rain stops. Making the characters look wet represents a significant challenge for the developers, however. A whole new set of character animations would need to be built for each stage of "wetness," and hardware and memory limitations would make adding all these extra frames untenable. A well-known graphical adventure game, Loom (LucasArts, 1990) features an animated scene where the player's thickly robed avatar dives into a lake, but then emerges as dry as he was before-no water drips from his robe and his feet leave no damp prints behind him. The same is true for the much later adventure game The Longest Journey (Funcom, 1999). After emerging from an underwater world back onto dry land, the player's character is told by her companion that "She is dripping wet," yet this condition is not reflected graphically. In each of these cases, showing the wetness may be possible, yet the costs in storage space and processor time have often seemed too great to justify doing so. Realistically simulating weather in a virtual environment is simply not possible without powerful graphical processing hardware. As in The Longest Journey, the difficulty in showing state changes connects weather to difficulties in showing changes in player characters-whether this is in player character’s visual representation or in the aspects of the player character that affect the rest of the game world, as in many games where the player character’s foot prints can be followed by enemies or when blood alerts enemies to the presence of the player character.

Weather as Dramatic Action

Realistic weather might play other roles in games besides simply reinforcing the coherence of the virtual world. Countless novels and films allow weather to play a critical dramatic role. Novelists and filmmakers long ago realized the conscious and subconscious significance of weather and often make it an integral part of their narratives. One of the most clichéd opening lines in all of fiction is "It was a dark and stormy night," a sentence that gives the reader an idea of the time and the weather-but, more importantly, sets the tone for an eerie and frightening story. In countless films, a sudden, violent rainstorm coincides with the dramatic experiences of the characters-a convention that has even been self-consciously parodied in several comedy films: "What next, rain?" And then it falls. Clearly these authors and directors are taking advantage of the connection that weather conditions have on our moods; if we are "moody," we might very well describe ourselves as being "under the weather." My point here is that given the preponderance of dramatic roles for weather in other media, we might find it odd that there are so few in videogames-particularly those with strong narrative elements (like The Longest Journey or Myst that could clearly benefit from them).

Conceivably, depicting realistic weather would be easier if it could be described in text rather than high-resolution graphics. However, even without having to worry about displaying it, developers still face considerable challenges simulating and incorporating the weather into their games. Some text adventures do tell the player if it is raining or thundering in that part of the virtual world, though these facts of the virtual world seldom affect gameplay. The player could still move about and act as normal whether it were raining or not; the only difference might be that the text "It's raining" or "You hear thunder in the distance" may appear from time to time under the normal descriptions of the spaces the player's character travels. The weather conditions described in these games seem to have much less of an effect on the player's character than such events would have on us in real space. However, weather plays a much more significant role in some interactive fiction titles. Montfort, author of Twisty Little Passages, points out two text adventures where weather plays an important role: Andrew Plotkin's A Change in the Weather (1995), and Brian Moriarty's Wishbringer (Infocom, 1985). These games implement weather in strikingly different ways. Plotkin's game begins with the player extricating himself from an unpleasant picnic to wander about a lovely park. As one might guess from the game's title, soon enough, the weather soon changes. Though many reviewers of the game cite its "cruel" difficulty as a serious flaw, almost all of them agree about how effective Plotkin's skill at altering the mood of the game through the use of weather. Many of the scene descriptions change after the weather becomes violent. A reviewer named Duncan Stevens contrasted two such descriptions as particularly well-managed:

Before the storm:

You're standing on a ledge, on a rather steep, overgrown hillface. Greenery hides the stream below and the hilltop above, and the meadows and sky beyond sweep away into the incandescent west.

After:

You're standing on a ledge, on a rather steep, overgrown hillface. Rain hides the stream below and the hilltop above, and to the west is only dark (Stevens, "A Change").

These excerpts give some idea of the considerable gravity that weather changes can bring to a virtual environment, even one accessible only via text. The same scene seems more menacing and foreboding now that the description has taken a "change in the weather" into account; the effect adds dramatic tension as well as verisimilitude.

Wishbringer makes a much different use of weather. In this game, the central conceit is a "wish stone," which the player can use to wish for things necessary to solve puzzles. Several puzzles can be solved by "wishing for rain." Here, the weather is treated as just one more variable the player can control (a technique also practiced in the game Weather War). However, considering Wishbringer's magical setting, the weather is contextualized within a specifically unreal articulation of the weather and of the environment. It creates a world based on ecological tropes that is also simultaneously divorced from those tropes. In the Wishbringer world, the gameworld’s ecology is just one more power that can be brought to bear to aid the player on her quest, rather than a vulnerable and fragile entity requiring responsible treatment.

Perhaps a more interesting genre of videogames for researching weather is the Multi-User Dungeon (MUD), which, like text adventures, eschew graphics, but feature coherent virtual worlds populated with other players as well as "bots" or "non-player characters" (NPCs). Several also feature "global weather" and changes in seasons. Online forums designated for discussion about MUD development host threads about how these features can be implemented or improved. Most MUDs that feature effects like rain do so purely at random, though the server keeps up with the location and coverage of rainstorms as they move across the virtual world.

One MUD developer named Shane P. Lee suggests that coders look to flight simulation programs for good weather algorithms: [Modern flight simulators] "can not only 'predict' the future weather, but also have different weather depending on how high you are in the sky" ("Re: Local"). Lee also points out that several online databases contain real-time weather information that can be adapted for use in virtual environments. Surprisingly, respondents to several other threads about weather voice their opposition to the incorporation of realistic, effective weather conditions in MUDs, citing that such things would add complexity but not necessarily make the MUD more fun. Lee himself writes that "one of the least concerns a player has is what the weather is like, so having a really cool weather system is like having really cool underpants, you are probably going to be the only one who actually who appreciates it" ("Re: Local"). Here again, on the one hand, players seem to think additional realism assists immersion, yet some things are better left to the imagination and need not be represented-indeed, representing them can actually make immersion more difficult by frustrating or aggravating the player. As one respondent pointed out, we play games to escape reality. "There is a point where a game is too far advanced to be fun anymore," writes Cameron Carroll, a frequent player of the MUD Alsherok (Carroll, 2002). By "advanced," Carroll is referring to complexity, and how many variables and controls affect the player. Each layer of complexity asks more of players and does not necessarily make a game more fun to play. Indeed, much of the charm and enduring popularity of ancient games like chess is the simplicity of their rules. Developers need sensible reasons for making a game more complex; "realism" is not always sufficient. Games like Sim Earth that allow players too much freedom and too little gratification may be doomed to failure in terms of player entertainment because many players need sensible limits and clear indicators of the effects of their decisions. The addition of weather does not have to offer greater complexity in terms of difficulty; however, the increased depth in any given game may make a game too difficult to play.

As Samuel Johnson wrote long ago about drama: "It is justly considered as the greatest excellency of art to imitate nature; but it is necessary to distinguish those parts of nature which are most proper for imitation" (Johnson, 1992, p. 318). For Johnson, one of the chief skills of artists is their ability to select and represent only those dimensions of life that demonstrate the highest virtues. In The History of Rasselas, Johnson has Imlac say that the poet "does not number the streaks of the tulip, or describe the different shades in the verdure of the forest. He is to exhibit… prominent and striking features and… neglect the minuter discriminations" (Johnson, 1992, p. 320). Imlac's metaphors echo current obsessions among graphic card developers, who boast that the next generation of videogames will be able to represent individual blades of grass. Of course, one problem with Imlac's advice for artists is that we could not determine whether a feature is indeed prominent or striking unless we see it presented in context. For instance, ordinarily, we would not wish to view a character in a movie relieving himself, and would be right to consider such activities, though perfectly natural and experienced daily by each of us, better kept off screen. We do not ordinarily wish to experience that degree of realism. Yet in the context of the film The Madness of King George, the "king's water" plays such an important role that the scene is indeed quite striking and effective.

For various reasons, we do not need weather effects in every videogame, or even in most of them. Rain in Tetris would be a dubious enhancement indeed. However, some games would benefit greatly from such additions. There is little doubt that SimCity is better for its earthquakes and other natural disasters, and artillery games like Scorched Earth (1991) would be too easy without wind. Random magnetic storms and meteorites add nicely to M.U.L.E. Many games that do not feature realistic weather are clearly the worse for it. For instance, Myst III: Exile, developed by Presto Studios (for Cyan), features very impressive photorealistic graphics throughout. Even the water appears like actual water, glistening and always moving. However, players looking up at the sky see beautiful but stationary clouds. Such a moment is likely to draw attention to the game as such. On some levels I heard thunder crashing in the distance and looked up to see dark clouds approaching from the distance. However, several long minutes revealed that the developer had only switched one static cloudscape for another; there was no movement in the sky.

Although for games like Myst III, cloud rendering is probably more trouble than it would be worth, it makes a tremendous difference for other genres. In particular, developers of flight simulation games (flight sims) have made realistic weather simulation a key selling point. Microsoft Flight Simulator 2004: A Century of Flight features one of the best weather simulation technologies ever designed. It is worth reflecting for a moment why, of all possible genres of videogames, flight sims would see the most radical innovations in terms of depicting realistic weather conditions that have non-trivial effects on the player's avatar (an airplane). The answer is the peculiarities of the flight sim niche compared to other types of videogames. Although some popular flight sims do feature narratives or goal-oriented missions like other games, most flight sims offer players non-structured experiences (even mission-based games typically have a "free flight" option to let players enjoy the virtual flight without interference). To put it simply, players just want to experience what it is like to pilot various types of aircraft. Flight sim developers compete to produce the most believable and true-to-life experience possible, including the addition of realistic weather-a factor which everyone knows is critical to real aviation.

Microsoft Flight Simulator 2004 allows players to download "real-time" weather from the net. Thus, if it is raining in the real San Francisco, it will also be raining in that city when the player flies over it in the game. In some ways this is comparable to Pete Sampson's "expensive planetarium" hack for Space War!; do players really care if the virtual world of their videogame mimics these aspects of the real world? If this were the only innovation in Microsoft's new version of its classic sim, there would be little cause for fanfare. However, the developers went a step further and introduced a new cloud-rendering system that may have implications for many other genres. Clouds, of course, are a vital characteristic of the weather, yet representing them believably in videogames has long thwarted even the largest game development teams.

In an article for Gamasutra.com, the online version of Game Developer Magazine, Niniane Wang describes some of the challenges developers have faced in the past in generating realistic clouds. "The interactive nature of games necessitates that clouds must look realistic whether the camera is far away, next to the cloud, or traveling through it" (Wang, 2004). Furthermore, clouds “need to be shaded appropriately to emulate both sunlight and light reflected from the sky… spanning dawn, midday, dusk, and night" (Wang, 2004). Wang describes the many different approaches to cloud rendering taken by past developers. Their attempts failed either because they asked too much of the computer's hardware (and caused the game to skip or jitter), or unacceptably limited the artists' control. For instance, an artist relying on a fluid dynamic cloud-rendering system may have to spend hours manipulating variables to achieve the cloud pattern she desires on the screen. Other developers tried to "paint clouds onto the skybox texture," but the problem then was that the clouds always appeared to be the same distance away.

Microsoft Flight Simulator 2004 not only generates clouds; it generates three types (cumulus, stratus, and cumulonimbus) and allows players to fly their planes through them. T. Baker, who reviewed the game for Game Spot, remarked that "the addition of true 3D clouds that drift through the sky and merge into one another as weather conditions change adds a realistic touch to the game that static screenshots simply can't convey" (Baker, 2003). "These aren't just the white cotton balls we've been seeing in every sim since Jane's World War II Fighters five years ago" writes a reviewer for Game Spy (Chick, 2003). Clearly, these achievements in representing clouds are necessary preconditions for representing rain. The virtual worlds of future games will likely feature rainstorms preceded by a gradual thickening and darkening of the clouds, though the question remains whether game designers will want to artificially control these effects for the sake of narrative or sacrifice this control for the sake of realism.

There is at least one other game worth mentioning in any scholarly treatment of weather in videogames: Ouranos! (1980), also known as Weather War, is a small game written in BASIC by Kathy Higby for the Commodore PET. A relatively obscure title, Ouranos! is significant because it actually makes a game of the weather. Essentially, players sheltered in opposing cabins took turns slugging each other with rain, hail, tornadoes, and lightning. Each turn, players select the "weapon" of choice and a "charge," which must be calculated based on the wind speed and direction (given at the bottom of the screen). The game was later updated by Bob Carr of Magic Carpet Software and released as Weather War II for the Commodore 64. Carr also made some other alterations: the cabins have been replaced with castles, a detail which suggests a magical fantasy setting (which might suggest how the players are able to control the weather in the first place). Unfortunately, much like the aforementioned Wishbringer, the player’s manipulation of the weather has no effect on the game’s ecosystem. Perhaps we might find the game more satisfying today if the castles were replaced by polluting factories, and the players competed to see who could destroy them first. We might also wonder what the long-term consequences of such weather-tampering might have for this virtual world. Keeping one's castle intact would make little difference if the world's ecosystem was wreaked in the process. Thus, a relatively simple (yet enjoyable) game about weather could become a moral lesson about humanity’s role as planetary stewards.

Conclusion: The Future of Weather Simulation in Games

There are countless games that incorporate weather, many in thought-provoking ways. I could have mentioned Lakitu, the cloud-piloting turtle villain in Super Mario Bros. or discussed educational titles like Discovery Channel Interactive's Operation: Weather Disaster.

As videogame hardware and software continues to progress, games will present better and more realistic weather simulations. Weather simply plays too important of a role in the real world to be ignored in virtual ones, particularly those that strive for realism-cinematic or otherwise. Perhaps we will also eventually see games taking a more environmentally responsible approach to representing weather-one imagines game worlds in which a player’s negligence could lead to acid rain and deadly global warming. It will also be interesting to see how believable rain and other weather effects, rendered in real-time, can enhance, influence, or determine a game’s narrative elements. Will future games observe a player’s actions, determine her mood, and generate the correct weather? While weather as a dynamic force has not been fully explored, other natural systems like disease are beginning to emerge in MMORPG’s like World of Warcraft. The plagues in World of Warcraft point to possibilities for emergent systems that (in/a)ffect gaming worlds while referring to worlds outside of the game space. The Serious Games Initiative, the Learning Games Initiative, and others are studying games for their game- and real-world implications. While weather has yet to achieve its full evolution in gaming, game design and game studies are poised for weather’s larger possibilities-possibilities that shape gameworlds as well as the real world, whether through weather mapping, simulation or cultural perceptions of weather and its operations. Within the larger context of ecology, weather is a single aspect of the larger intricately interdependent relations of systems and objects. For games, depicting weather is part of depicting larger worlds, and larger fields of significance. In fact, the weather in games shows how significance in game worlds can translate into significant real world relations.

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