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The History and Theory of Sandbox Gameplay

In this in-depth Gamasutra analysis, game professional Breslin examines the history and current state of the 'sandbox game', looking at modern games like Grand Theft Auto IV and Spore to see how they fulfill the concept of unlimited, unfettered creativity.

[In this in-depth Gamasutra analysis, game professional Breslin examines the history and current state of the 'sandbox game', looking at modern games like Grand Theft Auto IV and Spore to see how they fulfill the concept of unlimited, unfettered creativity.]

It's such a buzzword nowadays -- sandbox. It is a very abstract concept, like "liberty" or "love," so there are a lot of varieties. Modern sandbox games draw from a wide range of design structures: from open-world design to emergent behavior, from automation of believable agents to multi-threaded or non-linear story.

Being applied in such a broad range of situations means that the word "sandbox" risks its meaning becoming watered-down, confused, and sometimes forgotten.

On the other hand, it remains the single most important design issue for current and future generation games. It's a great blessing to spend a while in serious thought, on such a critically defining idea.

Let us take this opportunity, then, to reflect upon the different ideas we as gamers and designers have of the notion. Let us think about where the whole idea came from, and consider where we've come to, as we look toward the many futures of this wonderful little concept.

Just to get rolling, let's consider the concept in abstract:

The Ironies of the Metaphor

The concept of sandbox-style gameplay, as we know, suggests more-or-less undirected free-play. The metaphor is a child playing in a sandbox: the child produces a world from sand, the most basic of material. This in contrast to a game where the upper-level content is presented fully formed and ordered.

The metaphor of "sandbox" suggests something pure and free. It implies that it is a young child in the sandbox (and a pre-videogame child at that, with no toys), and assumes an idealized childhood imagination, an unlimited creativity. It is a good metaphor, and a useful one, but the metaphor is also a little misleading, insofar as it suggests a sort of dream-world imaginative capability of the audience, which is not always justified.

The implications of the metaphor are not necessarily carried over by game designers: we anticipate that less imaginative players will get less out of a sandbox game, and this is fine. But even so, the idea of leveraging the player's imagination is quite ambitious, and more than a little risky.

By itself, this design concept is so ambitious -- "give them a sandbox, and they will build castles" -- that it must be met with a far greater investment in making the sandbox actually work, which generally means much more money and time invested across all levels of production, and particularly upper-level design and writing. It means an especially close relationship between programming and upper-level design, with the anticipation that the upper-level design will often determine the lower-level specifications.

If normal game design is developing upper-level material (missions, etc.) based on an engine, sandbox design is writing an engine to express upper-level gameplay concepts. Of course, it's very silly to put it so simply as that: indeed, game production is always a back-and-forth between programming and design.

But basically, sandbox design requires the development of engines which enable open exploration in various ways, engines which support upper-level sandbox design by providing systems for the handling of the sandbox elements. It's fun work for a systems programmer, but it's not easy. Then, on the upper level, sandbox requires design which emphasizes and encourages free-play, as well as the development and implementation of a wide range of dynamic interactive elements.

And it's not just the presentation of the sandbox elements and the play space, but it's handling all of the player's various interactions, all the possible combinations. To say it very simply, a typical game must respond to correct input, while a sandbox game must reward all input.

While a physical sandbox is very easy to build (compared with most other toys), the sandbox game generally requires far more work than similar, less open and responsive games. Unlike the person who builds a physical sandbox, a sandbox-style game designer cannot simply offload the creative effort onto the gamer.

The Necessary Framework

Unfortunately, sandbox design is sometimes taken to justify the exact opposite: "sandbox" sometimes serves as an excuse for less investment, particularly in high-level design. Sandbox elements can be mistakenly taken as fair replacements of narrative content; indeed, many games have missed their potential because they imagined that free-play would compensate for a lack of narrative. But even for our idealized child, playing around in a physical sandbox gets old pretty quick.

This principle design problem of sandbox-oriented gameplay is already subtly suggested by the sandbox metaphor itself: a child playing in a sandbox needs a lot of direction if they're going to have very much fun. They need toys first, and they need to be given ideas of things they can do with them. The parent needs to provide a meaningful framework. Just dropping a kid in a sandbox does not work.

The same is true of sandbox design. If the design effort fails to produce a game rich in intriguing potential, it's very much like shipping a literal sandbox. -- Imagine a game-box literally filled with sand: the open-minded player might enjoy playing in the sand a bit, but the gameplay really isn't worth a lot.

The necessary framework guides the presentation of the sandbox elements as the world develops and unfolds. This is often expressed as a reward system, which can involve new areas to explore and new stuff to do, more difficult gameplay structures to navigate, more story unfolding, more missions becoming available, and so on. It can be based on exploring the space of the game (exploring Liberty City for example), and it can be based on watching the game-world develop over time.

It often means scattering a great number of narrative elements across the game-world for the player to discover. Rather than presenting the sandbox as "here's a box of toys, goodbye," the framework gives some strategic order to the game's elements, a presentational structure -- and thus it gives the player periodic rewards for playing.

A common misconception is that the stories of sandbox games are not determined by the game's developer: instead, the story is supposedly determined and directed by the player. But even designers of the most free-form sandbox games must specialize in producing worlds which are geared towards making that free-play fun. If the sandbox is interesting (and this is by no means guaranteed!), then the game's potentialities, the potential interest and fun -- including the narrative undercurrent and whatever else makes the free-play engaging and worth the time -- are all very carefully handled by the developer.

"Sandbox" sometimes challenges traditional narrative, but it always puts something new in its place. -- Thus, it does not remove the narrative, but rather transforms predetermined narrative into dynamic, responsive narrative. In other words, the sandbox game distinguished itself by making the responses more significant and meaningful.

This is perhaps contrary to an image of sandbox play which emphasizes pure freedom, but again, sand by itself is not much fun. Automated, complex, and perhaps most of all, directed responsiveness is essential to sandbox play, and the more complex and responsive the world, the more interesting the sandbox.

What is interesting about the sandbox form is not that it allows full freedom, but that it generalizes and parameterizes, it finds arenas for agency and gently crafts the potential space of the game. It fosters a sense of free-play and exploration of that space. It engenders a sense of player control, without actually handing over the reins entirely.


Prelude: Leisurely Play, Discovering Elite

As popular gaming moved from the arcade into the living room, the stage was set for a less frantic, more leisurely presentation of the action -- gaming "off the clock."

No longer was there a need to kill the player off as quickly as possible, in order that he (or the people waiting in line behind him) insert another quarter.

It became feasible and even desirable to give the player a break from the action, some time to thoughtfully explore his environment, rather than race him towards inevitable destruction.

Thus were born a number of popular gaming genres, including the adventure game and the flight simulator.

The adventure game popularly began in 1978 with Warren Robinett's breakthrough game for the Atari 2600, entitled, appropriately enough, Adventure. 1980 saw the release of the more sophisticated and seminal Rogue and Ultima.

This genre moved through the popular classic Pitfall and the unforgettable catastrophe E.T. (both, 1982). The player now had his leisure -- his world was now basically open. Pac-Man had broken out of his labyrinth -- and found a real world waiting for him outside.


Adventure

A seemingly distant genre, the flight-simulator, popularly began in 1980 with subLOGIC's appropriately-titled Flight Simulator, later licensed to Microsoft. These games were groundbreaking for the sense of freedom -- and what better sense of freedom than flying through the open air? Their basic problem was that the air was empty, so there was literally everywhere to go and nothing to do. The game was the movement alone.

Movement alone is a fantastic concept for gaming, of course, as has been well demonstrated by recent parkour-inspired games (Assassin's Creed, Mirror's Edge), and the closely-related genre of sports games. Also, exploration is the fundamental gameplay concept of open-world games. So, even while the early flight simulators were devoid of narrative or action, they were perhaps the first pure expression of open-world joy.

Then there came Elite (1983), which synthesized these emerging forces, and in so doing shifted the paradigm.


Elite

Elite was outstanding in many ways. Its graphics engine was original and groundbreaking: wireframe 3D graphics with hidden-line removal was a big deal back then. The auto-generation of the universe was brilliant, and its combat was clever (although dogfighting had already been incorporated by subLOGIC/Microsoft's Flight Simulator back in 1982). Its economy was a game just by itself, and it had a rich gameplay all around.

But Elite was truly profound because it presented a game-world space and a freedom of movement and choice that for the first time felt real and unbounded. The game-world no longer appeared to be a closed labyrinth or a hilly continuum, but was now an open universe -- and so the game-world metaphor began to operate on a new level.

With The Seven Cities of Gold (1984), this was of course the birth of a genre: the trade/exploration/combat/adventure sandbox, typically in space or at sea (key metaphors of freedom). The successors are far too numerous to list, but they include: Starflight (1986), Pirates! (1987), Star Control (1990), Privateer (1993, and following), X (1999, and following), Freelancer (2003), Darkstar One (2006), SpaceForce 2 (2007).

In the whole history of computer games, there have been only two other innovations which are on the same level as this moment: 1) the explosion of multi-player; and 2) the paradigm-shift from 2D "platform" to 3D world -- the latter already anticipated by Elite's cockpit view, though this was already done in the popular arena by the arcade game Battlezone (1980).

(Technically speaking, Jim Bowery's 1974 game Spasim was the first multiplayer 3D combat, but as it ran on a PLATO network mainframe, its audience was relatively small and specialized.)

However, it would be about sixteen years before game designers began to use the term "sandbox" to describe this kind of free-form play. Nevertheless, the concept of the open game-world is essentially the same, from Elite all the way to Assassin's Creed, Spore, or GTAIV.


Building

The intervening years saw many trends in free-play, the most popular of which was the city-building game. It began in 1982 with Utopia, but the city-building genre really came into its own when it ceased to be strategic/competitive and became instead an exercise in "free" building for its own sake.

The genre grew out of the natural pleasure of designing game-worlds -- a pleasure that game developers experience all the time. One developer, Will Wright, thought that it would be a good idea to share this joy as directly as possible, and this insight led to the development of SimCity, which became a record-breaking success, defining one of the largest genres of the 1990s.

Sometimes this sort of free play was blended with economic simulation, in such as the Tycoon games, starting with Railroad Tycoon (1990). Various more-or-less competition- and objective-oriented games joined its ranks throughout the following decade, from SimIsle to Capitalism (both 1995).

Opening game design to the player, even to a very limited degree, heralded modern player-generated-content games, from Second Life to LittleBigPlanet to Spore.

Encouraging Player Experimentation

The metaphor of the "sandbox game" finally emerged at the turn of the century, around the publication The Sims and the following year, Grand Theft Auto III, the two games which are traditionally considered the two original and canonical "sandbox" games.

The invention of the term did indeed accompany a new development in game design, but this was not, as the term suggests, player freedom, which was already available by any number of means: non-linearity; the lack of objectives or central storyline; automatic variation of the game-world and game-behavior.

It was in terms of responsiveness and encouraging player experimentation that these games represented a gradual but transformative change in game design.

"Sandbox" was a new development because it indicated a new promise: automated responsiveness to player behavior. In this sense it does not mean "free play," "non-linear," and the rest; rather, it indicates that which makes this style of play specifically and particularly interesting in its own right.

Most of all, this meant a radical development in design detail. The evolution of sandbox-oriented quality between GTA2 and GTAIII is truly astounding. The switch from bird's eye to 3D opened the world and shifted it from cartoonish "Hot Wheels" platformer to a realistic city. But the critical part was that the writing and detail followed through on the promise.

As mentioned at the beginning, sandbox design facilitates and encourages a sense of player freedom, while providing a framework for play and a rich and detailed world for interaction. This was definitively achieved by The Sims in 2000, and in 2001, Grand Theft Auto III. Let's now consider their innovations, starting with The Sims.

Towards Believable Characters: Psychological Games, A-Life, and AI

The amazing commercial and cultural success of The Sims might suggest that it was entirely new -- which means we are likely to forget that the genre began with Little Computer People (1985), even though the latter "game" was well celebrated in its time.


This is the birth of the mind game, the virtual seduction.

There were several studies in the 1990s, of what gameplay structures and presentation/interface regimes increase attachment, what exploits the player's tendency and desire to interact in a seemingly meaningful way with the artificial character. These always somehow literalize the metaphor of the game-world, bring the player into the virtual space and enmesh him there: enabling "physical" contact (mouse-petting), sharing "space" (e.g., the player and the character can manipulate the same on-screen objects), and so on.

Today we are so close to such virtuality that it has perhaps become difficult to observe its mechanism, but a primary aspect of sandbox play is the formation of a psychological illusion of contiguity, if not continuity.

Thinking more towards psychologically effective programming, let us consider the dual nature of AI. As any AI designer or programmer will tell you, the task of designing a "believable NPC" involves fostering an appearance or impression of that elusive philosophical notion of intelligence: the psychological impression of intelligence.

What contributes to this impression, however -- the underlying program -- is more or less "intelligent" in an entirely different sense. Where we speak of the "intelligence" of the program, we mean only the level of autonomy and generality. This is not the place to get into the specific maneuvers and techniques, but be assured that relatively simple programming can lead to really convincing NPC AI, and really it's mostly in the presentation.

The NPC programmer's plan, then, is essentially to write suggestive and interpretable behavior, so that the player will "read in" a lot more sophistication than is actually present. Computer-players can be good at winning a chess match or a combat, which has relatively simple rules, easily-validated success cases, etc.

But beyond this, the question of truly intelligent programming (in that ephemeral, philosophical and psychological sense) is well beyond our technological horizon and may well remain there forever. The question of NPC personality in games is always the question of faking it.

The main reason that this trend towards believable characters is compelling for sandbox play is that the characters are, at bottom, more dynamic and interactable. They help "sell" the game world because they seem more realistic. Not "realistic" in the sense that they can ever hope to pass the Turing test, but realistic enough that they'll lull you into forgetting about their artificiality. The more intelligently the NPCs respond, the more the game feels like a free and open world.

AI is widely various and can be complicated, but in general it is effect-oriented. The programmer has in mind a goal behavior, and writes code to meet this objective. In comparison with AI, Artificial Life is bottom-up programming, and it's all about emergence. The emergent behavior is not necessarily even known in advance.

The Sims, and especially the range of games it inspired, was heavily influenced by technological developments in computer science during the 1990s, and in particular Alife. By 2000, this has developed into the art of manipulating automated NPC behavior, even in an otherwise traditional title, as we have for example in Majesty.

In this classic, there is no player-character, and little if any direct action by the player. Instead we have NPC agents whose behavior cannot be directly controlled, but only indirectly influenced in some way: add stimuli and enjoy watching how the automatons respond. It's a delightful gameplay model, which we look forward to revisiting in the forthcoming Majesty sequel.

Playing with automated systems, watching NPC AI agents interact with each other according to their program, or even watching Alife virtual organisms go about their daily life, has long been and remains a key sub-genre of sandbox play. Further, believable and self-motivated characters have become key to sandbox play, because they produce a rich space for interactivity and greatly help establish the open-world aesthetic. But in another style of sandbox games, the game space itself plays this role....


A Realistic World: Emergence, Robust Simulation

An emergent behavior is a consequence of the rules. Take the rules of, say, chess: the rules of chess do not explicitly refer to the concept of initiative or that opposite colored bishops tend to be drawish. But these and many other characteristics of the game are determined by the rules. We see emergent behavior in many complex physical systems (fluid mechanics in physics, for instance) -- or more to the point, we see it in the material happenings of any complex game world.

The various characteristics of explosive barrels in Doom is one canonical example. The rules which govern their behavior are very simple; nowhere does the program say anything about how they can be lined up for a chain reaction.

Once barrels started exploding in chain reaction, the virtual world had suddenly become robust, palpable, realistic. This was an amazing moment, but very little of the player's energy was invested in playing with the system -- yet. Doom struck a highly linear and simple tone, for it did nothing to encourage the player to experiment with the scenario.

From a certain point of view, Doom could be considered a sandbox: we remove the "EXIT" and the player wanders around killing baddies, doing as he likes. From the same point of view -- and this bears especially on how we commonly use the term nowadays -- the production of a "sandbox" game is a subtractive operation: subtract the missions, the main campaign, the narrative or whatever formatively binds the game's progression, and you have a "sandbox." The player can fool around without doing anything "on task" or so.

This is the sandbox we mean when we speak of "Sandbox Mode" (as opposed to "Campaign Mode"), and it is closely similar to how the term is used in software development.

In general terms, if one removed the objectives of a game to produce unguided play, or lack of narrative, one would makes a sandbox in some subtractive sense -- but not in a productive sense. True sandbox design means adding game behaviors which, in combination, produce interesting emergent behavior, but it also means adding some reward for free play. Emergence is good, but a free-play oriented framework is also necessary.

Metaplay and the Multiplayer Arena

While meta-play and multiplayer are certainly two entirely different phenomena, they have some things in common and they often happen simultaneously, so we might consider them loosely together.

Meta-play normally means a different approach to playing, where the player is no longer playing the game as it was designed, but messing around with it and doing amusing things. This includes exploring glitches, testing the game's limits, creating and pursuing personal objectives, and other things which were not necessarily intended by the game's designers. "Hmm, I wonder how many resource harvesters I could build..." or "How far can I drive off the track, and what happens then?" or "Can I finish the game without getting the spider ball?" -- this kind of play.

This relates back to our opening discussion of adventure games, whose design tends to be in the form of lock-and-key puzzles. One implicit challenge in such games, and one way by which mastery can be measured, is in figuring out the shortest route.

When the game is played in this attitude, the metaphor of adventure falls away, and the player instead thinks consciously of the underlying system, how to optimize given the rules of the system -- and even how to break the rules of the system. Though it operates on a different level, sequence-breaking is very sandboxy and very meta, and lock-and-key style adventure design encourages it, from Super Metroid (1994) to Switchball (2007).

The key here is that the game might support sandbox-style playfulness or meta-play, whether or not it was designed to do so. Sandbox is a much wider genre in terms of play than it is in terms of explicit design: a wide variety of games can be played in a sandbox style -- it just depends on the ingenuity and creativity of the player.

Even chess can be considered a sandbox game, if you look at it in the right way. It need not even be played as a competition: instead, you and your opponent could cooperatively explore the potentialities of the game, to see how certain interesting structures can emerge -- to "meta-play" the game, not competitively, but critically, analytically, imaginatively. (One could well argue that if you look at chess in the right way, meta-play happens quite frequently over the course of a normal competitive game.)

Indeed, any sufficiently complex game can be considered a sandbox if one of the aims of the players is to explore the implications of the game's rules. The metaphor of "game world" becomes strained, but it is possible to liken the space of potentiality opened by the rules to a game world, which the players can freely explore.

The point is that it does not take two opponents to play chess; instead, one can play in a creative way -- solving the eight queens problem, for instance, or producing an elegant endgame. The traditional card game solitaire is not really a sandbox game; but a solitary game of chess can be. The interesting point here is that there is a space of free-play potential even before the opponent enters the scene.

The case is similar with multiplayer: the game need not be specially designed to support rich sandbox gameplay; it needs no carefully-crafted narrative framework, no believable characters, and so on. By contrast, it takes only a modest arena to produce all the necessary strategic interest to support a rich multiplayer experience. Even the simplest of MUDs can do it. When it comes to multiplayer, we can strip things down quite a bit, as the opponent provides much of the necessary framework.

This is no argument against complex multiplayer worlds. World complexity often leads to more nuanced strategy, which is a good thing. But speaking minimally, all a multiplayer arena really needs is a set of rules.

Likewise, if the player approaches the game in either an ironic, analytical, or deeply-invested way, then the experience can rest on the simplest of pleasures -- such as riding horses around together in a wilderness, and looking at a randomly-generated landscape.

But on the other hand, if we subtract multi-player, or we subtract that meta- level of player interest, even the most realistic game-world can lose its interest very quickly. A realistic simulation can be a great multiplayer arena, and a great foundation for building a game-space, and it may indeed be fun to explore for a little while. But it must be recognized that realistic simulation on the one hand and gameplay/presentation on the other are very different phases in development, and if the principle challenge and purpose is not being supplied by multiplayer, then some directing framework must be supplied by the designer.

User Generated Content

Game design itself is, undoubtedly, the ultimate sandbox game: you the designer get to determine the game's objectives, and not only that, but also create and assemble the artwork and other presentation elements, balance the game as you see fit -- create a whole world to play in.

Modding is quite similar to game design in that sense. The main difference is that modders do not write game engines and they do not design the larger framework. Their role tends to be limited to top-level design, though of course this varies from game to game.

Ten years ago, one would be wise to remark that "the future of gaming is modding." But over the course of the past decade, modding itself has become increasingly part of playing the game, and the line between playing and modding is now and forever blurred. From the simplest "scenario editors" of the late 1990s through Neverwinter Nights modding tools, to Crytek's Sandbox, game production has increasingly focused upon in enabling and encouraging player design, and today's games often present certain forms of design as a core ingredient of the gameplay.

For years, modders have been using Maya rather than Creature Creator. Spore's obvious innovation is that now every player gets to mod. Spore is not alone in this, of course. Indeed, LittleBigPlanet is arguably even more progressive in this area. The key is the creation of a game that works towards the objective of player-generated content, and designing tools to enable novice modeling and design.

We will be discussing Spore as a special case study, below. The salient point here is that while Spore makes an art of erasing the difference between modding and playing, the same thing has been done for years in a less integrated and novice-friendly manner, but far more completely.

Second Life is still another canonical example of a game that is designed to be modded. It produces an amazingly real analogy between (on the one hand) the clothing designer, construction worker, or architect/engineer, and (on the other hand) the 3D modeler. Players are sometimes even paid for their 3D models in real money, just as real-life carpenters are paid for their cabinetry work.

Whether people play perfected visions of themselves or ironical caricatures, the combination of multiplayer and modding assures a permanent place for Second Life. On the other hand, one key element is that there is no game-worthy interest. It is a pure sandbox, and so it suffers a lack of interest, from a lack of what we have been calling 'framework': a lack of direction.


Contemporary Case Studies

One of the best ways to evaluate the state-of-the-art of Sandbox design is to consider modern expressions of the design. General theo

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