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Game Design: Theory and Practice, Chapter Seven
The Elements of Gameplay
By Richard Rouse III
Gamasutra
June 27, 2001
URL: http://www.gamasutra.com/features/20010627/rouse_01.htm

This excerpt from Richard Rouse III's Game Design: Theory & Practice, covers several key game design issues, which contribute to what Rouse calls "The Elements of Gameplay." The book covers all aspects of game design, from coming up with a solid idea to writing the design document, from implementing the gameplay to playtesting the final product.

"We ended up with a game that I didn't know how to win. I didn't know which were the best strategies or tactics, even though I designed all the game's systems. That is what makes a good strategy game."
—Julian Gollop, talking about his game X-Com: UFO Defense

What are the game design elements that make up a really good game? Of course, there is no definitive answer to such a question. Nonetheless, as a game designer you will be expected to intuitively know exactly what the answer is. Understanding game design, as with any art form, is very much an internalized understanding, a "gut" reaction, a "feeling" you might have. It may be that you will not be able to form that answer into words, but you will need to understand what aspects of a game are strong and which are weak, and how the latter can be replaced with more of the former. Experience plays a big part in understanding what makes a game fun, experience both as a game designer and as a game player.
Over my years of playing and creating games, I have come up with my own answers for what makes a game great, and in this chapter I discuss some of those qualities. Some of these topics may seem fairly distinct from each other, yet to my mind they all play a crucial role in making a good game. Certainly, I cannot hope to list all of the knowledge I have, since, as I mentioned, much of my understanding is more akin to a "sixth sense" than anything I could hope to write down in a book. But the ideas contained in this chapter should help to give you a starting point.

Unique Solutions

For me, one of the most exciting moments of being a game designer is when I hear someone talking about playing one of my games, and they explain a successful tactic for a given situation that I had never considered. This could be a solution to a specific puzzle, a way to incapacitate challenging enemies, or a method for maneuvering a perilous canyon. I see the games I develop as creating situations in which game players can utilize their own creativity to succeed. When the player's creativity can lead them to solutions, which I had not envisioned, it shows me that my game is doing its job.

Anticipatory versus Complex Systems
Good designers will try to guess what players are going to attempt to do and make their game respond well to those actions. For instance, take an RPG that features a puzzle that involves placing weights on a series of pressure plates. (Having put such a puzzle in a game of my own, I would like to implore game designers to be a bit more creative than that, as pressure plates are surely one of the most overdone puzzle devices still in use. But I digress.) Suppose the designer leaves a conspicuous pile of rocks a few rooms over from the pressure plate puzzle. The obvious solution to the puzzle is to use those rocks on the pressure plates to achieve the desired results. But what if the player tries dropping his various weapons on the plates instead? This is a perfectly valid solution which should work equally well, provided the player has weaponry of the appropriate weights. What if the player has the Summon Minor Threat spell which allows him to summon a variety of different small monsters? If the player summons those monsters onto the pressure plates, they might do the trick too.
Now the designer, having thought through the puzzle fully, can have the programmer add in code where the game reacts correctly if either rocks, weapons, or monsters are on the plates. This is the anticipatory school of game design, where the designer thinks what the player might do and hardwires the game to work well with those actions. I agree that this tactic is surely better than allowing for just one solution. However, what if the player thinks of some other weight he can place on the pressure plates? What if the player uses his Berkshire Blizzard spell on the pressure plates, causing snow to fall on them? Enough snow could conceivably pile up on the plates to have a significant weight. However, if the game has been hardwired only for rocks, weapons, or monsters, the game will not react appropriately. The player will have thought of a perfectly reasonable solution and the game will fail to recognize it.
Instead of hardwiring, however, what if the designer had the programmer come up with a system where every object in the game had a weight associated with it? This would include rocks, weapons, monsters, weather effects, blood, and anything else found in the game-world. If the programmer then made the pressure plates simply get the weight of all of the objects on top of them, regardless of their type, then this one, global solution would work for all objects. If each object was set up with a reasonable weighting, it would not matter what object the player tried to place on the pressure plates, as they would all work automatically.
This latter method is less of an anticipatory system of game design; it is more holistic in its approach. It relies more on creating reliable, consistent systems with which your game will function. Then, for a puzzle such as the pressure plate one described above, the designer and programmer come up with a series of success conditions for that puzzle. Instead of "the puzzle is solved if the player uses rocks, weapons, or monsters to offset the plates," the rule is "the puzzle is solved when the plates are offset by the correct weight being placed on top of them." Certainly, the example of this puzzle is a simple one, but the same techniques can be applied to much more sophisticated and interesting systems which engender a wide variety of successful playing styles.

Emergence

The Civilization games are some of the best examples of complex
gameplay emerging out of multiple consistent systems running in
parallel. Pictured here: Civilization II.

It is the development of numerous robust and logical systems that leads to player-unique solutions to situations in the game. One could describe these solutions as "emergent" from the systems design of the game, a popular buzzword in game design circles. Establishing a game universe that functions in accordance with logical rules the player can easily understand and use to his advantage allows players to come up with their own solutions to the problems the game presents. Nothing can be more rewarding for the player than when he tries some obtuse, unobvious method for solving a puzzle or a combat situation and it actually works. The more complex systems that work correctly and concurrently with each other, the more interesting and varied the solutions to situations become. Consider the game Civilization, with its numerous systems running in parallel. These systems work together to create some of the most compelling gameplay ever pressed to disk.
Another example of this sort of emergent strategy can be found in the original Centipede. Anyone who has ever played the game knows that the piling up of mushrooms is one of the greatest impediments to a long game, and many players understand the importance of keeping the play-field as clear as possible. As the devotees of the game pumped quarter after quarter into the game, they began to notice some patterns. First, they recognized that the flea is responsible for dropping most of the problematic mushrooms, though destroyed centipede segments also drop them. Second, they saw that the flea does not come out on the game's first wave. Third, it was observed that the flea is triggered by the absence of mushrooms in the bottom half of the screen. Thus the famous blob strategy was developed, one that the game's designer, Ed Logg, never anticipated. To use the blob strategy, the player would clear all of the mushrooms from the board on the first wave, and then allow mushrooms to survive only on the bottom-right quadrant of the screen. If, through careful destruction of the centipede, the player only allows mushrooms to be created in that section of the screen, the flea will never come out, making the game much simpler indeed. This is an emergent solution to racking up a high score at Centipede, one which players no doubt felt quite proud of when it was discovered. Furthermore, it was a discovery that Logg, as the game's creator, did not even know was there to be found. That is good game design.

Non-Linearity

Non-linearity is another buzzword in the game industry, and well it should be. Non-linearity is what interesting gameplay is all about, and many designers forget this in their work. Non-linearity gives interactivity meaning, and without non-linearity, game developers might as well be working on movies instead. The more parts of your game that you can make non-linear, the better your game will be.
In general, when someone says something is linear they mean that it follows a line. A line is a series of points connected in either two- or three-dimensional space, where one can find any point on that line using a specific equation, such as, in a 2D case, y = mx + b. In layman's terms, this means that a line must be straight. If one considers any two points on that line, say A and B, there is only one way to navigate that line from A to B. There are no choices to be made; one simply must navigate all of the points between A and B. Outside the world of mathematics, we can consider reading a book to be a linear experience. If one is reading a 323-page book and if one does not skip pages or chapters, there is only one way to read the book: by starting on page 1 and reading all of the pages leading up to page 323.
Games, however, are non-linear works. In playing chess, there are multiple ways to capture the opponent's king, to move from the game's predetermined starting state to its conclusion. Indeed, there are a vast number of different ways to be victorious in chess, and that variety is what keeps the game interesting. These choices make chess non-linear. Suppose the chessboard were one-dimensional instead of two, each player's pieces could only move in one direction, and each player had only one piece. This version of chess is a linear one, since there are no meaningful choices for the player to make and the outcome of every game is completely predetermined. And, of course, it is not a whole lot of fun either.

Types of Non-Linearity
So when we say we want our games to be non-linear, we mean we want them to provide choices for the player to make, different paths they can take to get from point A to point B, from the games beginning to its end. We can mean this in a number of ways: in terms of the game's story, in terms of how the player solves the game's challenges, in terms of the order in which the player tackles the challenges, and in which challenges the player chooses to engage. All of these components can contribute to making a game non-linear, and the more non-linearity the developer creates, the more unique each player's experience can be. Furthermore, the different non-linear components can interact with each other to make the whole far greater than the sum of its parts.

Storytelling: I discuss non-linear storytelling in more detail in Chapter 11, "Storytelling." Of course, a non-linear story line is necessarily tied to non-linear gameplay, and no one would bother to try to make a story non-linear if the game itself offered the player very little in the way of meaningful decisions. Storytelling is perhaps one of the most neglected parts of games in terms of non-linearity, with many developers allowing for non-linear gameplay while constraining their games to a completely linear story.
Multiple Solutions: I discussed above how a well-designed game will enable the player to come up with his own solutions to the challenges the game presents. Not every player will think of the same way to go about solving a situation, and, given that these alternate solutions are reasonable, any challenge must have multiple ways for the player to overcome it. Having multiple solutions to the individual challenges within a game is a big part of non-linearity; it enables the player to have multiple paths to get from point A (being presented with the challenge) and point B (solving the challenge).
Order: Beyond being able to figure out the solutions to challenges in unique ways, players will enjoy the ability to pick the order in which they perform challenges. Many adventure games have made the mistake of being overly linear by allowing the player access to only one puzzle at a given time. In order to even attempt a second puzzle, players must complete the first one. That is a linear way of thinking, which proves especially frustrating when a player gets stuck on a particular puzzle and, due to the game's linear nature, can do nothing else until that puzzle is solved. Giving the player choices of different puzzles to solve allows them to put aside a troubling puzzle and go work on another one for a while. After completing the second puzzle, the player may return to the first, refreshed and revitalized, and thereby have a better chance of solving it.
Selection: Another way of making a game non-linear is to allow the player to pick and choose which challenges they want to overcome. Say that between point A and point B in a game there lies a series of three challenges, X, Y, and Z, which are non-order dependent, that is, the player can do these challenges in any order he wishes. What if, once the player surmounts challenge X, he does not have to go back and solve challenge Y or Z, he can simply move on to point B in the game, perhaps never returning to Y or Z? The same is true if the player initially chooses to tackle Y or Z instead of X. Any one of the choices will allow the player to proceed. The advantage is that if the player finds challenge X to be insurmountable, he can try challenge Y or Z. This greatly decreases the chance of the player becoming permanently stuck. It need not be the case that Y is easier than X; the mere fact that it is different may allow the player a better chance of getting through it, depending on his strengths as a player. Other players may find X to be easier than Y or Z, but giving the player a choice of which challenges he takes on allows the player to exploit his own personal skills to get through the game. Of course, after completing challenge X, the player may still have the option of going back and completing the Y and Z challenges, perhaps just for the fun of it or because overcoming those challenges somehow improves his chances down the line. Perhaps completing Y and Z gives his player character greater overall experience or riches. This type of non-linearity can also be used to add totally optional side-quests to the game. These challenges are not strictly required for the player to get to the end of the game, though they may make it somewhat easier or merely provide an interesting diversion along the way. Whatever the case, these optional challenges provide an extra degree of non-linearity, further customizing the player's experience.

Implementation

Odyssey is an extremely non-linear game, allowing the player to
solve puzzles in whatever order he chooses and to select which
quests he wants to go on. The game almost always provides more
than one solution to any given puzzle.

My first game, Odyssey: The Legend of Nemesis, is without doubt the most relentlessly non-linear game design I have ever done, and includes examples of all the types of non-linearity described above. Odyssey is an RPG and takes place on an archipelago that includes seven primary islands for the player to explore. Though the player is required to complete at least one quest on the first island before moving on to the rest of the game, there are two quests, each with multiple solutions from which the player may choose. Indeed, clever players can skip the quests entirely if they figure out how to rob a particular townsperson. From there, the player is able to move freely about the next five islands, picking which ones he wants to explore and which he prefers to just pass through. Indeed, all that is required for the player to reach the seventh island and the end-game is for the player to successfully navigate each island, killing the monsters that get in his way. Of course, killing those creatures is made significantly easier if the player receives the rewards for completing the quests. But if the player so chooses, he can skip the entire middle of the game. Of course, few players have done this, preferring instead to explore the different quests and situations they encounter there. Nearly every single one of these quests has multiple ways for the player to solve it, with his actions having a direct impact on how each of the island's mini-stories resolves. Finally, the game itself has multiple endings for the player to explore, endings which suit the different overall goals the player may have: survival, revenge, or a sort of justice and harmony. Though the game had a very definite story, I am happy to say that I doubt very much that any two players ever experienced it in exactly the same way.
Non-linearity is an extremely powerful tool to use in designing a game, and the descriptions above of the types of non-linearity a designer can employ may seem obvious to the reader. What is astonishing, then, is how many games fail to provide any substantial non-linearity for the player, instead insisting that the player play through the game on a single line from point A to point B. One reason for this is that creating all of these non-linear elements can be quite time consuming. Consider that between point A and B, we have the aforementioned challenges X, Y, and Z, but the player only has to overcome one of these challenges in order to progress, say challenge X. The player can then continue playing through to the end of the game having never interacted with challenge Y or Z. As a non-linear game, that is the player's prerogative. The problem arises when a cost accountant looks at the game and tries to figure out where the game's budget can be trimmed. Well, obviously, if Y and Z are not strictly necessary, why bother having them at all? Why spend a lot of money on the programming, art, and design necessary to get Y and Z working when there's a chance the player will never see them? Unfortunately, accountants are often not in touch with the finer points of game design, and when you say, "But non-linearity is what makes this game great!" they are likely to dismiss you as "difficult."
Non-linearity is also often hard to pull off from a design perspective, certainly harder than simple linearity. This may be another reason why so many designers shy away from it at the first opportunity. Designing numerous obstacles that are different enough to provide variety for players while all applying roughly the same challenge is not an easy task. In the X, Y, and Z challenges example, if Z is significantly easier than X or Y, it is quite likely no one will ever bother with X or Y. In a way, a game with poorly designed choices for the player is nearly as linear as a game without any choices at all. The non-linearity your game provides must be meaningful and useful to the player or it is a waste. Designers who think too highly of their own design skills may also avoid non-linearity in their designs because they want the player to experience every single element of the game they decide to include. "Why spend a lot of time on portions of the game that not everyone will see?" say these egotistical designers, starting to sound a lot like the accountants.

The Purpose of Non-Linearity
It is important to always remember that non-linearity is included in the game to provide the player some meaningful authorship in the way she plays the game. If forced to stay on a specific line to get from the beginning of the game to the end, the player will tend to feel trapped and constrained. The challenges along that line may be brilliantly conceived, but if the player has no choice but to take them on in order, one by one, the fun they provide will be greatly decreased.
Non-linearity is great for providing players with a reason to replay the game. Replaying a game where the player has already overcome all of the challenges is not that much fun. In replaying a more non-linear game, however, players will be able to steer away from the challenges they succeeded at the last time they played and instead take on the games other branches. However, it is important to note that replayability is not the main motivation for including non-linearity in your game designs. I have heard some game designers complain that replayability is unnecessary since so many players never manage to finish the games they start playing anyway. So if they never finish, why add replayability? These designers do not realize that the true point of non-linearity is to grant the player a sense of freedom in the game-world, to let each player have a playing experience unique to himself, to tell his own story. If the player wants to replay the game again, that is fine, but the primary goal of non-linearity is to surrender some degree of authorship to the player.
Furthermore, the contention that players seldom finish games and hence the games do not need to be non-linear is a self-fulfilling prophecy. The reason players fail to finish games is often because they become stuck at one particular juncture in the game. This may be a boss-monster who is too difficult, a puzzle that is too confounding, or merely failing to find the exit from a given area. If the game were more non-linear, however, players would have much less chance of getting stuck at any point in the game, since the variety of paths available would increase the likelihood that the player's unique talents would be sufficient for him to make it successfully past one of them.
At a Game Developers Conference talk entitled "A Grand Unified Game Theory," Noah Falstein suggested that when non-linearity allows the players to tackle a series of required challenges in whatever order they desire, completing one challenge should make the others easier for the player to accomplish. In the case of a collection of puzzles, this can be done by providing the player with a hint about the other puzzles once he completes one of them. In the case of a collection of battles of some sort, this can be done by providing the player with additional weaponry with which to survive the other battles. Whatever the case may be, using this technique increases the chance that the player will be able to overcome the challenges at hand and get on with the game.
A note of caution: all designers should understand that non-linearity is not about having the player wander around the game-world aimlessly. If the game is non-linear to the point where the player has no idea what she is supposed to try to accomplish or how she might go about it, the non-linearity may have gone too far. Often game designers talk up their in-development games by making statements like "In our game-world, the player can do anything they want; there are no restrictions. The game is completely non-linear!" Such a game would likely be completely annoying as well. Of course, by the time these completely non-linear games have shipped most of the non-linearity has been stripped out and the player is left solving puzzles on a rail. Somewhere between on a rail games and total freedom lies an ideal middle ground, where the player is left with a sense of freedom accompanied by a sense of guidance.

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