What Way Is It Meant To Be Played? Florian Mihola March 2020 Abstract and home video game consoles digital inputs were the standard up until the “16-bit” era of the 1990s. The most commonly used interface between a Sony PlayStation, Nintendo 64 and Sega Saturn fi video game and the human user is a handheld are among the rst which brought with them ad- “game controller”, “game pad”, or in some occa- ditional analog controls—either at launch or as an sions an “arcade stick.” Directional pads, analog updated controller option. And even though mod- sticks and buttons—both digital and analog—are ern mass-market offerings include analog sticks linked to in-game actions. One or multiple simul- and analog triggers, digital buttons and directional taneous inputs may be necessary to communicate pads remain the ubiquitous fundamentals of input. the intentions of the user. Activating controls may The simple nature and widespread use of digital be more or less convenient depending on their po- inputs leads to a degree of interoperability: Game sition and size. In order to enable the user to per- software is not necessarily tied to a single game fi form all inputs which are necessary during game- controller—whether we interpret this as a speci c play, it is thus imperative to find a mapping be- model, a design and protocol available by different tween in-game actions and buttons, analog sticks, manufacturers, or a class of generic controllers— and so on. We present simple formats for such but can be enjoyed using a range of controllers, mappings as well as for the constraints on possi- provided they share at least some common char- ble inputs which are either determined by a phys- acteristics. When a game releases for multiple ical game controller or required to be met for a contemporary platforms, differences in controls game software, along with methods to transform tend to be limited to different naming conventions; said constraints via a button-action mapping and emulation of a so-called “retro game” most often to check one constraint set against another, i.e., to calls for a minimum number of inputs; on plat- check whether a button-action mapping allows a forms for which no single standard controller ex- fi controller to be used in conjunction with a game ists an appropriate controller choice and con gu- software, while preserving all desired properties. ration are frequently left to the user. But the decision which button mapping to use or whether a pair of controller and game “fit” at 1 Introduction all is not as straight-forward as it might seem— especially so if we aim for more than the mere fea- sibility of gameplay. From the earliest days of arcade games up till present day, a variety of input devices have been How should controllers, games, and button map- explored. Pong uses paddles, Pac-Man moves in pings be encoded and how do we decide whether four directions via a four-way stick; there are steer- an instance of all three combined will deliver an en- ing wheels and pedals, light guns, and even skis joyable experience? to ride on. But apart from so-called “dedicated The rest of the paper explores how it re- cabinets”—which use controls which are tailored to lates to other work in the general area of in- a specific game—most arcade cabinets use a dig- terest in section 2, gives an introduction to ital eight or four-way stick—most often alongside our method—section 3—followed by a more for- a number of digital buttons. In home computers mal explanation—section 4—and some insights 1 into software implementations—section 5. Sec- Game & Watch series of handhelds—which use the tions 6 and 7 discuss a variation on, and an ex- kinds of digital inputs we are most interested in; re- pansion to our method and sections 8 looks back minding us of an interesting case study, albeit with as well as forward—concluding what has been rather simple controls. learned and anticipating future research. Go, Konishi, and Matsuura [4] describe “IToNe”, an application of dual analog joysticks for enter- ing japanese text. It might be feasible to model 2 Related Work this approach of partitioning a joysticks range into zones corresponding to japanese kana using our Reasonings along the lines laid out here, or meth- approach; it remains to be seen what, if anything, ods similar to those presented, are likely to have of interest could be added in this vein. been employed in practice, and one may very well deliver excellent playability of video games either with a fixed control scheme, or in the case of 3 Overview games which do not put stringent requirements fi on button con guration, or simply do not use a Guided by motivating examples, we will first give great number of inputs. We nevertheless maintain a somewhat informal introduction to the central that, in order to properly discuss such techniques, ideas and methods of this paper, followed by for- spread their use in game and emulation software, mal definitions in section 4. and to build a common vocabulary, it is necessary Starting with a simple notion, consider the num- to give accurate accounts of models and related ber of inputs required to play a game in relation to algorithms in an academic setting. the number of inputs found on an input device. In Most of the sources we discovered barely over- a 2D platformer we might find the game to react fi lap with our speci c topic, but there is a range of to four directional inputs and an additional jump works which are of interest to the same audience: command. A four-way directional pad and a but- Skalski et al. [10] examine how natural mappings, ton should suffice. The games requirements and using controllers like Nintendo’s Wii motion con- a simple controller are succinctly represented as troller affect game enjoyment. While the intersec- sets G and C. tion of controllers allowing for such natural map- pings and the ones in the focus of our method is G = {left, right, up, down, jump} small, we pursue similar goals of furthering game C = {dpad , dpad , dpad , dpad , enjoyment and ease of playability. Another in- left right up down vestigation into natural mappings by Shafer, Car- buttona , buttonb } bonara, and Popova even poses the question “Con- troller Required?” [9]; this is clearly related to— Via a mapping of buttons to game controls such but also very different from—our interest in tradi- as {dpad left → left, dpad right → right, dpad up → tional gamepads. Seemingly in contrast, a study up, dpad down → down, buttona → jump}. It can by Rogers, Bowman, and Oliver [8] alludes to situ- be swiftly argued that it is possible to perform all G ations where a traditional control scheme may in desired in-game actions described by using the C some aspects outperform motion controls. controller described by because if we replace ev- G Alves et al. [2] apply so-called “Design Think- ery element of with the corresponding element C G ing” techniques to designing novel game con- in we obtain exactly set , meaning all game trollers; some designers consider hybrid ap- controls are connected to controller inputs in some proaches where physical inputs are combined with way. Expanding on this example, assume the game touch screen controls. character has the additional ability to run at dif- ferent speeds, which shall be controlled by hold- Button layouts—not of physical controllers, but 1 virtual layouts for games played on touch screen ing down a run button. Instead of simply expand- devices—and their generation are discussed by ing the previously mentioned sets and mapping we Alves, Montenegro, and Trevisan [1] and Baldauf 1It is not by accident that this control schemes resembles et al. [3]. The later article mentions Nintendo’s the one found in Super Mario Bros. 2 opt for a more sophisticated approach. In order to able to use various input combinations contain- perform longer or higher jumps it is necessary for ing left or right—but never both—we could also the player to not only have access to a jump and opt for the converse approach and specify that run button, it is paramount that the user is able to left and right—likewise up and down—build sets of push the two corresponding buttons at the same buttons (or of in-game actions respectively) which time. In addition we want to express that it should may not be pushed (active) simultaneously. We not be possible to activate simultaneously both left may further encode that a button shall be operated and right or both up and down. Along with the con- with the left—or right—hand, that two actions shall straints imposed on the game’s controls, the struc- be mapped to a pair of buttons found in a sym- ture of the sets representing both game require- metrical configuration on a two-hand controller, or ments and controller facilities increases in com- the organization into “face buttons” versus “trig- plexity. Sets like {jump, run} or {right, run} form ger buttons”. One may need to employ multiple the elements of what is now a set of sets repre- such predicates to adequately represent all de- senting all combinations of inputs which shall be sired qualities, and it shall sometimes be benefi- possible to be activated simultaneously. We arrive cial to replace the “naked” elements employed so at set far with a predicate notation like Facebutton(jump) or Simultaneous(buttona , buttonb ).