Your game s input and output systems are two of the primary factors that determine how steep the learning curve for your game is and whether players will find it intuitive to play. Using the input/output systems you design, players must be able to control and understand the game effortlessly. Designing these systems is one of the hardest aspects of game design, since, if they are designed well, players will not even know they are there. But if they are designed poorly, players will become easily frustrated, complaining that the game s controls prevent them from doing what they really want to do in the game. Designing input and output systems is an invisible art in that the goal of their creation is for them to be transparent to players. This can sometimes lead to designers failing to fully consider how to best make the I/O work in their game, a mistake you must avoid if you want your games to be any fun to play.
Nothing is more frustrating to players than knowing exactly what they want their game-world character to do but being unable to actually get her to do that because the controls will not let them. Good gameplay is never about trying to figure out the controls themselves ; though you may want puzzles in your game-world, your control scheme should not be a puzzle players need to figure out. The controls are the players interface between the real-world and game-world. In order for players to experience true immersion in the game they must be able to manipulate the game-world almost as intuitively as they manipulate the real-world. Every time players have to think, Now, what button do I have to press to do that? that immersion is destroyed .
Though the controls for many computer games seem to be getting more and more complex, particularly those for 3D action games, there is a lot to be said for keeping your controls simple. Indeed, a lot of the success of games like Diablo , Command & Conquer , and The Sims can be attributed to the fact that players can play these games one-handed, controlling everything with only the mouse. The mouse is an extremely powerful input device when used correctly. Its great strength is that it is a control device with which most non-gamer computer users are already familiar. This makes mouse-only games very easy to jump into, since they minimize the time the user must spend learning controls.
A big part of designing a good mouse-based interface is making a system that does not look as sterile and business-like as theWindows file manager yet retains its ease of use. Making the interface look attractive is mostly a matter of well-conceived art, but making it attractive without losing any of its intuitiveness and functionality can be quite challenging. Whenever an artist suggests making a button look a certain way, the designer must consider if the new design takes away from the player s ability to understand how that button works. Often, you can borrow clearly understood icons from other interfaces, either from other games or from real-world devices such as VCRs or CD players. For example, everyone knows what a fast forward symbol on an audio device looks like, and using this appropriately in your game will mean that players instantly know what a given button does. Making buttons in your game that players can intuitively understand and that also look attractive is equal parts creativity and playtesting. If a majority of the people playtesting your game tell you your buttons are unobvious and confusing, they almost definitely are, and you need to return to the drawing board.
A common game design mistake is to try to include too much. This applies to all aspects of gameplay, but particularly to controls, where sometimes the clich less is more really holds true. Every time you add a new button or key to your game, you must ask yourself if the complexity you have just added to the game s controls is worth the functionality it enables. When designing a PC game, the temptation is particularly great, since the keyboard provides more keys than any game would ever need to use. Unfortunately, some games have tried to use nearly all of them, binding some unique function to practically each and every key. Complex keyboard controls favor expert players while alienating the novices, leading to a radically decreased number of people who might enjoy your game. Due to the limited number of buttons they provide, console control pads are much more limiting in what they will allow the designer to set up.
Unlike many other designers, particularly those making the switch from PC to console, I often feel that this limitation is a good one. Control pads force the designer to refine her controls, to cut away all that is extraneous, and to combine all of the game-world actions players can perform into just a few, focused controls. This leads directly to games that are easier to learn how to play. Indeed, many of the most accessible console games do not even use all of the controller s buttons. Because of the massive keyboard at their disposal, designers of PC games are not forced to focus the controls of their games in the same way, and I think their games may suffer for it. As I mentioned above, some of the most popular PC games have managed to squeeze all of their core controls into the mouse.
Much of the increasing complexity of game controls can be attributed to the increasing dominance of RT3D games. These games, by trying to include the ability for the player s game-world surrogate to move forward and backward, up and down, sideways left and right, turn left and right, and pitch up and down, have already used a massive number of controls while only allowing players to move in the game-world and do nothing else. In many ways, the perfect way to simply and intuitively control a character with total freedom in 3D space is still being explored. This is why for some time very few of the successful 3D games released allowed players total freedom to control their character. With the console success of complex first-person shooter-style games such as Halo and Medal of Honor: Frontlines , players seem to have grown accustomed to the intricacies of freely moving and looking around in an elaborate 3D environment. Nevertheless, in order to allow players a fighting chance, the most popular 3D games, such as The Legend of Zelda: The Wind Waker , Max Payne , Grand Theft Auto III , and Tomb Raider , continue to restrict player character movement to a ground plane.
One technique that can be used to make your controls intuitive to a variety of playersis to include multiple ways to achieve the same effect. For instance, if one looks at the interface used by the RTS game StarCraft , players are able to control their units by left-clicking to select the unit, then clicking on the button of the action they want the unit to perform, and then left-clicking on a location in the world where they want the unit to perform that action. Players can also left-click on the unit to select it and then immediately right-click in the game-world, causing the unit to do the most logical action for the location the players clicked, whether it means moving to that point or attacking the unit there. Furthermore, StarCraft also allows players to access a unit s different actions through a hot key instead of clicking on the button. This has the pleasant side effect of keeping the interface simple enough for novice players to handle, since it is all point-and-click, while the expert players can spend their time memorizing hot keys in order to improve their game. In many console action games, different buttons on the controller will perform the same action. A common choice to make, particularly on PlayStation games, is to allow players to control character movement through either the left directional pad or through the left analog control stick. Crash Bandicoot , for instance, allows players to move with either the directional pad or the analog stick, and also allows players to access Crash s ability to slide by pressing either a trigger button or one of the buttons on top of the controller. Providing multiple ways for players to achieve a single game-world action helps to ensure that a given player will enjoy using one of the ways you have provided.
There is a lot of room for creativity in game design, but control design is not one of the best areas to exercise your creative urges. Your game should be creative in its gameplay, story line, and other content, but not necessarily in its controls. Some of the most successful games have taken control schemes that players were already familiar with from other games and applied them to new and compelling content. Sometimes the established control scheme may be weak, but often it is not weak enough to justify striking out in an entirely new direction with your own control system. As a designer you must weigh what is gained through a marginally superior control scheme with what is lost because of player confusion. For example, Sid Meier s fine RTS game Gettysburg! included as its default method for ordering troops around a click-and-drag system instead of the established click-and-click system found in other games. His system was quite creative and actually may have been a better way of controlling the game than the established paradigms . However, it was not so much better that it outweighed the confusion players experienced when first attempting to play the game, a fact he admits in the interview included in Chapter 2 of this book. Console games are particularly good at providing uniform control schemes, with fans of games in a particular genre able to pick up and immediately start playing almost any game available in the genre , even if they have never seen it before.
During the course of the development of a game, as you are playing the game over and over and over again, it is very easy to get accustomed to bad controls. Though the controls may be poorly laid out or counterintuitive, as a game s designer working on a project for several years , you may have used the controls so much that they have become second nature. However, as soon as others play the game for the first time, they will quickly be frustrated by these controls and are likely to stop playing as a result. Indeed, when I ran Drakan: The Ancients Gates a few years after it shipped, I was immediately stunned at how bizarre and disorienting the controls were, particularly the ability to look left and right on the PS2 s right analog stick. Other members of the team I showed it to were similarly shocked. We shipped it like that? they said incredulously. Over the course of three years developing the game, we had grown familiar with the game s oddities and the controls seemed fantastic. With some distance between ourselves and the game, we were able to see its glaring control problems. Ideally, a proper playtesting phase will include many players playing the game for the first time, and witnessing their initial reaction to the controls is crucial to understanding how intuitive your controls really are. Do not think, Oh, she ll get used to it, or What an idiot! These controls are obvious; why can t she see that! or Well, I like them the way they are. Instead think, Why are my controls bad and what can I do to fix them?
Designing controls that players will find intuitive can be quite challenging, especially with such a variety of control setups for different games, particularly in the PC market. For example, back when the FPS genre was first establishing itself, it was hard to determine what the standard controls for an FPS should be since the last three successful FPS games had all employed unique control schemes. Thankfully, over time, the controls became standardized, and now fans of shooting mayhem are easily able to jump into almost any FPS they come across. Almost every PC action game released in the last decade allows players to configure the controls however they desire, and this is an absolute must for any PC game that demands players manipulate a large number of buttons. That said, many players never find or use the control configuration screens, either because of a desire to start playing the game immediately or a general lack of savvy with the computer. Many, many players will be left playing with whatever the default keys are, and this is why it is the designer s job to make sure these default settings are as playable as possible. Here, following the standard set by most other games is very important. You should never use a strange or confusing set of default controls for your game merely because the programmer in charge likes it that way or the team has grown accustomed to them. Always make sure the default controls are as intuitive as possible, and if this involves shameless imitation , so be it.
Making a game in an established genre is one thing, but when it comes to developing a game that tries to do something substantially new with what actions players can perform, there is no way to avoid spending a lot of time on the controls. After you get them so you like them, you must put them in front of players to see how well they work in practice instead of theory. Trying out brave new control styles is a noble endeavor, but you will need to make sure players actually prefer them to more traditional methods . And as you gather their feedback, long- term iteration is all but unavoidable. One example of this happened on my game The Suffering . The game was a shooter and we wanted to make it as console-friendly as possible, and thereby took Devil May Cry as a source of inspiration. At the same time, we wanted players to have the freedom to move through the environment and position and orient their camera like in first-person shooters or, specifically , Syphon Filter and our own Drakan: The Ancients Gates . So we developed a hybrid targeting system that provided players with intuitive movement through the world with a single thumb stick, but then allowed for simple targeting of enemies. We spent a long time developing this system and iterating on it, and felt we had done a pretty good job. Then we started hearing grumblings from fellow developers we showed the game to that the controls seemed odd. When we finally put the game in front of players their feedback almost universally mentioned the controls as what they liked least about the game. We tried tweaking it a bit more, showed it to some more players, and found that the controls still seemed odd. At this point we were fairly far into development and realized that the innovative control scheme we had attempted simply was not working out. Since it was the control system we were having a problem with, we decided it made the most sense to imitate some existing control schemes. We wanted something powerful that we knew players would be familiar with, so we copied the two-analog-stick scheme that most of the other current console shooters, including Max Payne and Halo , were using. At this point we were imitating instead of innovating , but when we put the game in front of players again with our new control scheme they almost all praised the quality of our controls and then were able to focus their complaints on other aspects of the game.
Particularly in action games, when your controls are perfect, the wall separating players from the game-world will disappear and they will start to feel like they truly are the game-world character. This is the ultimate sign of an immersive game, and achieving this effect is impossible without strong controls. In a game where that level of immersion is possible, the controls must be completely invisible to players. This can be frustrating to a designer. Why work so hard on something that, if implemented perfectly , will be completely invisible? The designer must realize that it is the transparency of controls that allows players to enjoy the rest of what the game has to offer.
While the player s ability to intuitively control the game-world may be key to a successful game, outputting vital information about that game-world to players is just as important. Computer games contain numerous complex systems, commonly performing more calculations than a human would ever be able to track. Indeed, that is the area where computer games excel. Condensing that massive amount of data into its most instructive form and communicating that information to players is key to a well-designed output system.
Consider a strategy game in which players have a number of units scattered all over a large map. The map is so large that only a small portion of it can fit on the screen at once. If a group of the players units happen to be off-screen and are attacked but players are not made aware of it by the game, players will become irritated. Consider an RPG where each member of the players party needs to be fed regularly, but the game does not provide any clear way of easily communicating how hungry their characters are. Then, if one of the party members suddenly keels over from starvation , the players will become frustrated, and rightly so. Why should players have to guess at or go digging for such game-critical information? In an action game, if players have to kill an enemy by shooting it in a particular location of its body, say its eye, they need to receive positive feedback when they successfully land a blow. Perhaps the enemy reels back in pain or screams in agony once an attack damages him. If players do not receive such feedback, how are they supposed to know they are on the right track? Of course, all computer games conceal a certain amount of information from players, and cannot possibly communicate all of the information they have about the game-world to players. But they must communicate what is reasonable and important for the players to know, and communicate that data effectively.
Almost all games present players with a view of the game-world as the central part of their output system. Through this view players see the object they are currently controlling and its location and state in the game-world. Your game should try to communicate as much information through this view as possible. Consider a third-person 3D action game. Certainly players see the environment and position of their game-world surrogate, but what about the condition of the player character? Perhaps as its health goes down, the character s animations change to a limp or hobble instead of moving normally. Similarly, the strength of the current armor can be represented by texture changes on that character, with the armor appearing more and more deteriorated as it takes damage and nears destruction. The game can represent the character s current weapon by showing that weapon equipped on the character. If players have a spell of protection currently in effect on their character, perhaps the character should emit a certain glow to easily communicate that. Though the designer may also want to include this data in a heads up display (HUD) of some sort , communicating it through the game s primary game-world view makes it that much more transparent and easy for players to understand.
What the game-world view cannot represent is typically contained in some sort of a GUI, which usually borders the game-world view or is overlaid on top of it like a HUD. This GUI may be simple, such as the high-score and lives remaining display on Centipede , the small potion-health display at the bottom of the screen in the original Prince of Persia , or the score/moves display in almost any Infocom game. For more complicated games, the GUI is also more complex, such as the button bars used in any of Maxis Sim games, the elaborate status display in the original System Shock , or the extensive party data provided in many RPGs, such as the Bard s Tale games. Many GUIs in older games were created in order to block off a large portion of the screen. This was not because of any sort of design decision, but instead because the game s engine was not fast enough to handle rendering the game-world full screen. As engine technology has improved, games have attempted to make the game-world view take up the majority of the screen, with the GUI minimized as much as possible.
A few games try to work without any GUI whatsoever. Crash Bandicoot , for instance, only displays the lives remaining GUI if players press a button to bring it on the screen; otherwise a completely unobstructed view of the world is displayed. Another example is Oddworld: Abe s Oddysee . The game s director, Lorne Lanning, felt very strongly that any sort of GUI would distance players from the game-world. As a result, Abe s health is communicated to players through the way he animates. Since the game grants players infinite lives, there was no need for a lives remaining display that so many console platformer games of the time included as their only HUD element. Certainly, as technology has allowed it, the trend has been to get away from on-screen HUDs as much as possible, allowing the game-world view to take over the screen. The advantages of the immersion gained by a minimized GUI are obvious, and if the game-world can effectively communicate all of the information the players need to play, there is sometimes no reason to use a GUI at all.
On the other hand, it is important to not go too far in the quest to eliminate a GUI. In general, a small, unobtrusive HUD is a game convention that players have grown accustomed to and thus are very unlikely to be bothered by. Though having no HUD worked pretty well in the Oddworld games, The Getaway is an otherwise fun game that suffered because of the developer s decision to avoid a HUD. Driving around London was needlessly difficult because, instead of having a map HUD, players were forced to navigate to their destination by making turns based on hints from the blinking turn signals on their car. This was a particularly imperfect and infuriating system when navigating the labyrinthine streets of London. Similarly, the game has no health meter, and players are required to use a considerably less precise and quite subtle player texture change to figure out their character s health status. Given the game s shooting and driving mechanics, leaving out the HUD hurt the gameplay far beyond the immersion that was gained.
The most important part of designing a GUI is to try to keep it as visual as possible. In fast-paced action games in particular, the GUI is designed to communicate information to the players very quickly, whether this is the players current health, ammo available, or nearby monsters (through some sort of radar). If anything, the ascendancy of the graphical user interface as the dominant mode of controlling a computer, first through the Macintosh and subsequently through Windows, shows that most people think visually instead of in numbers or words. As a result, a well-designed graphical HUD in your game will be easier for players to glance at and understand than one that contains a lot of numbers or words. This explains the superiority of the health bar over a health number or percentage. The artists will like a graphical HUD as well, since a health bar can look a lot more attractive than a big, ugly number. Though some amount of fine precision will be lost with a less precise health bar, players are willing to sacrifice this because the bar is so much easier to read quickly.
A game element that is particularly well designed is the head used in Doom and Quake . This face, which appears at the center of the bottom of the screen, represents the players approximate health completely visually. The face starts out healthy and snarling, ready to take on the world. As the players progress and they lose health, the head starts to look bruised and bloodied, eventually looking all but dead when players have almost run out of health. At any point during the game players are able to glance down at the head and instantly get a sense of how much health they have remaining. If the health had been represented instead by a number, it would have been much more difficult for players to comprehend their current health level just by glancing at it. The difference in time may be milliseconds , but in a fast-action game, that may be the difference between life and death.
Of course, the visual representation of data can also have a negative side effect if that representation is too obtuse for players to easily understand. For instance, in WarCraft , the buttons for the different actions that a unit can perform are all represented by icons, which I would generally encourage . However, some of the buttons can be a little difficult to figure out at first. Fortunately, the game also displays text at the bottom of the screen when the players mouse cursor hovers over a particular button, communicating what that button will do if clicked. What would have been even better is if the icons on the buttons were just a bit more obvious. Admittedly, representing a real-world action such as guard through a 32 x 32 icon can be quite a challenge. The GUI for your game needs to balance the superiority of visual representation with the clarity of text, possibly using a combination of both as needed.
Audio output as a communication device to players is something that is often underused in games. Not all of the information about the game-world needs to be communicated to players through visual stimuli. For instance, in The Sims , players gain a good sense of whether their character is enjoying a particular conversation based on the tone of the participants voices. In Command & Conquer , players know that a unit has received a particular order by an audio cue provided by that unit: I ll get right on it! Similarly, when units off-screen are being attacked, the game communicates this to players by saying Unit attacked or Unit lost. Audio cues can provide an excellent supplement to on-screen information, or can work quite effectively as the sole way of communicating critical information.
A good output system for a game is both powerful and intuitive. It allows players to jump right into the game and understand what is happening in the game-world, but it also provides expert players with all the information they need to play the game effectively. Over time, the data the game communicates to the players should become transparent, just as the players controls should become invisible once players are familiar with them. Players should not have to think about understanding the state of the world; they should just retrieve what they need by quickly looking at the screen, and then be able to react to it just as quickly through intuitive and responsive controls. As I have stated before, it is important not to get too creative in developing your input/output systems. The dominant paradigms from other games are often dominant for a reason: they work. The expression that good artists borrow but great artists steal is nowhere more true than in I/O design in games.