A User-Centred Approach to Control Design

It’s a familiar image – the furious slamming of fists into a laggy keyboard; the innocent mouse knocked aggressively from its perch; the once-glorious gamepad, now laying cracked on the floor beneath a film of cheese dust. Who among us has never resorted to blaming the controller for our own failures? And yet, in some cases, perhaps we are justified in our rage against the machine, for a poor control implementation can lead to any manner of misclicks, misunderstandings, and missed opportunities. Controls are a fundamental aspect of any game’s design, serving as a key factor in determining the game’s playability. Simply put, a game’s controls facilitate each and every interaction available to the player. This holds true regardless of input device – whether mouse and keyboard, gamepad, motion sensors, or brain-computer interface. No matter the input chosen, developers are tasked with designing a set of controls that is logical, easy to learn, fluid, responsive, and as unobtrusive to gameplay as possible. Ultimately, this process boils down to the creation of an interaction schema that effectively maps real-world actions, such as a button press or a wave of the arm, into an in-game action, like jumping or swinging a sword.

All of this rhetoric prompts us to inquire, how might we define good or great interaction design for game controls? We might assess a control scheme as effective if it is usable and contributes to a good user experience – that is to say, it enhances a player’s experience, rather than detracting from it. However, accurately measuring usability and user experience necessitates usertesting, which presumes that we’ve already implemented our design. May we determine some aspects of our design a priori as a pre-development measure, thus improving the quality of our initial efforts? The answer, thankfully, is yes, through the application of user-centred design, or UCD. UCD is a process oft-applied in the realm of productivity and web applications, though it is increasingly applied to the development of interactive entertainment, including games. In a nutshell, UCD focuses on understanding user needs, developing system requirements based on those needs, prototyping alternative designs, and finally evaluating the effectiveness of those designs. In this post, we’ll focus on how we can leverage the first two phases of UCD methodology – understanding needs and formulating requirements – to inform our designs pre-implementation.

Case Study: Designing Controls for Spirit

Our team’s interest in UCD is motivated by our current project, a 3D puzzle-platformer in a quasi-open world. Controls are of particular importance in the platforming genre, where players are frequently tasked with executing a precisely timed sequence of movement, jumps, and other abilities. Poorly-mapped or unresponsive controls spell disaster for any platforming game, as they maximize player frustration, or worse, make certain challenges impossible to complete. Our need for great controller design is compounded by the nature of our project in particular; since our core mechanic allows players to control a number of different objects, we may find ourselves designing a dozen control variants for any given input device. Furthermore, many of our puzzles are physics-based, demanding that our controls seem physically realistic while maintaining a good game feel. We’ve chosen to apply UCD in achieving these objectives to ensure that our players’ needs form the basis of our interaction design.


The first step in our design process is the establishment of our target user population, and an understanding of player needs based on their demographics, preferences, and past experience. Next, we formulate design requirements based on lessons learned from existing titles, expected use context, and player behaviours. Following this, we create our initial designs for three different player-controlled entities and refine them through early internal testing. Finally, we plan our next steps in usertesting and iteration to validate and refine our designs.

Understanding Players & Establishing Design Requirements

Our target audience for Spirit comprises players between the ages of 18 and 34 with at least a moderate amount of gaming experience. The ideal user will have fairly extensive experience with platforming games, enjoys exploration and puzzle-solving, and is willing to devote an hour or more to individual play sessions.

Based on the needs of our target players, we can categorize the requirements of our design into a few key groups:

Functional Requirements – What the controls should do.

For each set of controls, we need to support core game interactions – primarily, we are concerned with movement, jumping, interacting with objects, and manipulating the camera. Each interaction should be mapped to its own region on the appropriate input device, and real-world manipulation of the input should translate sensibly into in-game action.

Non-Functional Requirements – What the controls should be.

We’re developing Spirit for PC, so we’d like to offer both keyboard and gamepad support for players. Right now, we’re focused on interaction design for both mouse/keyboard and Xbox controllers. Since players will find themselves in situations where they might need to rapidly time jumps, precise changes in direction, or switching between objects, responsiveness and fluidity should feature prominently in the eventual implementation.

Data Requirements – What the controls should know.

Our controls need to respond differently depending on game scenarios – connecting with in-game feedback like contextual hints, restricting input when appropriate, and even responding to in-game physics. Thus, our control system should interface with game data to pull information regarding the camera, game state, position of interactive objects, and so on.

Context Requirements – How the controls will be used.

Since players will want to concentrate on what’s happening on-screen, we need to ensure that they won’t feel the need to glance down at the keyboard or gamepad to be sure of their next input. We expect that players will have prior gaming experience, and so our design can borrow from established conventions in the genre to assist in this effort.

Usability and Experience Requirements – What the user should perceive.

We want our controls to feel unobtrusive and fluid, minimizing the barrier that users perceive between their actions and in-game results. Controls should be easy to learn, and easy to use – we want challenge to come from puzzle-solving and platforming, not wrangling a gamepad. Lastly, we want players to feel good about mastering the abilities of any given object that they control, and so our controls should integrate with our animation and gameplay systems to create the most fluid experience possible.

Following the establishment of our design requirements, we examined (and played!) a number of different games. Since we’re concerned with designing controls for a several different objects, our research extended beyond the platforming genre to include games like flight simulators and shooters. For the purposes of our case study, we’ll look at the first few entities that we’ve implemented into our gameplay prototype – our main character, a beach ball, a marble, and a paper plane. Each design follows from a core set of universal attributes that we’ve developed based on estimated player expectations, with refinements to individual objects focused on improving game feel and maximizing usability.

Control Designs

Universal attributes. At its core, Spirit is a platformer, and so we looked at a lot of different platforming games to get a feel for the sort of controls players would expect – from classics like Super Mario 64, Banjo-Kazooie, and Chibi-Robo to modern incarnations of the genre, like Yooka-Laylee. We also played quite a bit of Ori and the Blind Forest – though a 2D platformer, the controls in Ori are outstandingly responsive and fluid, with snappy animations that respond near-instantaneously to most inputs.


Since players will be in a 3rd-person, 3D environment regardless of the object they’re controlling, we also looked at games like The Legend of Zelda: Breath of the Wild to learn from some truly great 3rd-person control schemes. Ultimately, we decided on a few standards from which we could build and refine each individual entity’s control scheme:

Locomotion. No need to reinvent the wheel on mapping basic movement – we’re going to keep primary directional movement on WASD for keyboard users and LS for gamepad players. We’ll map jumping to spacebar on keyboard, and A on gamepad. For each individual control variant, we’ll use the physical qualities of the entity that the player controls to determine how movement controls should behave – including acceleration, directional changes, and any animation delays.

Camera Movement. Following the aiming conventions of first- and third-person games alike, we’ll map this movement to RS and mouse movement. For keyboard and mouse users, we’ll allow toggling of locked and free camera modes with the tab key.

Interactions. We’ll map primary and secondary actions, like possessing objects and interacting with NPCs, to Q/E on keyboard and Y/X on gamepad. We’ve opted for a primarily one-button scheme (using E and X respectively), which will perform the correct action based on the interaction available in-world. To accomplish this, we’ll check for interactive areas within the player’s FOV and display a prompt in-world to highlight the available interaction.


Each of the control variants below is based on these core universal attributes, with variations based on the physical attributes of the entity in question, and any expectations players may have from previous gaming experiences.

Third-person humanoid. Players will spend most of their time as Spirit himself, a tiny ghost with roughly humanoid features. We want motion to feel snappy and responsive, so for this design, we’ll map the movement axes directly to the player’s velocity, with a slight acceleration timed to match the character’s run animation. We’ll base this on a character controller that considers game feel first, and physics second – to give players a fluid experience that integrates well with animation. Following the standard of most platformers and third-person games, we’ll allow players to “turn on a dime” – turning animations are nice and cinematic, but may prove frustrating when players want tight controls above all else. The result in-prototype looks something like this:


Round objects (physics-based). Two of our initial objects, the beach ball and marble, both follow a scheme inspired by the feel of locomotion in games like Katamari Damacy or Super Monkey Ball. In contrast to the main ghost controller, we’ll base this scheme almost entirely on physics, mapping movement axes to forces applied on the object, rather than instantly changing the object’s velocity. By configuring the amount of acceleration applied, we can create the feeling of a large, weighty rubber ball or a small marble with a tight turning radius. We’ll let the physics engine handle angular momentum, preserving it through jumps and collisions, to create an experience that feels more physically realistic. In past iterations, we experimented with more direct schemes that were less physics-based, as in the main character’s controls; the consensus from the majority of players was that they preferred and expected more physics-dependent behaviour for traditionally “inanimate” objects. The end result is a nice, responsive force-based controller that “fights back” if this object controlled is particularly weighty:


Flight (hybrid). Developing controls for a paper airplane was particularly interesting – though inanimate like the ball, the plane functions as more of a vehicle than a dead weight, and so we looked to spaceflight and flight simulators like X-Plane for inspiration. Stripping away the complexities of a bona fide flight sim, we can reduce the act of flight to a few primary controls – throttle (forward motion), yaw (turning), pitch, and roll.

Since throttle and yaw correspond to motion in the XZ plane, we can associate this with the “locomotion” controls for other objects – as such, we map throttle to the z-axis of movement (W/S on keyboard, or up/down on LS for gamepad) and yaw (which we’ll tie into roll, for smoother animation, to the x-axis of movement (A/D on keyboard, left/right on LS). Pitch and roll are a bit more interesting – in keeping with the conventions of traditional flight controls, we’ll lock the camera to the direction the aircraft is travelling, and use the axes freed up from camera controls to modulate pitch (up/down with mouse or RS) and roll (which, coupled with yaw, is offered secondarily by using left/right with mouse or RS). The result is something that feels like a simple, zippy little flight simulator:


Next Steps

Over the course of our work so far, communication among the dev team has proven crucial – our initial implementations have undergone many iterations to improve responsiveness, physical accuracy, and animation. However, we’re still very much at a prototype stage, and we’ll need to test our current variations with real players to validate and further improve our designs. Our next step will be finalizing control variants for a few more in-game objects, before proceeding to some early alpha testing with potential players. As part of our usertesting efforts, we’ll be integrating techniques like gameplay recording, questionnaires, and semi-structured interviews to understand our players’ perspectives on controls and interactions in our game. In the meantime, we’ll be working on improving in-game feedback to help users learn available interactions more effectively, and designing some simple puzzles to facilitate an in-game environment for testing where users will be able to focus most of their efforts on evaluating the game’s controls.

Overall, the UCD approach has proven immensely helpful to our interaction design process, improving the quality of our initial designs and our efficiency as a team. Be sure to check back in soon for an update on our creative direction and level design as we move forward from our initial prototype!

Shading Spirit

Over the past few weeks, our artist has been fleshing out the details of our final character model and starting on animations. And so, the time had come – no more placeholder shaders for the little guy. Time to sit down and take a crack at a custom surface shader for our poltergeist friend, and we already had a few key features we wanted in mind. Since the beginning, we’d had something in mind similar to the ghosts from Luigi’s Mansion: Dark Moon :

In particular, take a look at the little green guy – he was a big inspiration for Spirit’s character design and shows off some of what we’d like to achieve with our visual effects.

Let’s break down the visual features of the model:

  • Base colour (green)
  • Glowing eyes/mouth
  • Surface detail (bumps/pores)
  • Edge/rim lighting (white/green)
  • Exterior glow (green halo)

Additionally, we wanted Spirit to have adjustable partial alpha, so that he’d appear semi-transparent, for maximum spookiness. Most of what we want to accomplish (aside from the exterior halo, which we’ll add in post-processing) can be done with a standard surface shader in Unity. Here’s a list of the components we’ll need to integrate for each feature:

  • Depth pre-pass and alpha intensity
  • Albedo map and tint
  • Emission map
  • Normal map, intensity, and smoothness
  • Rimlighting map, intensity, and tint

And here’s the texture maps we’ll be using to achieve the final effect:


Unity’s built-in CG features make writing this shader pretty easy if you know which tools to use – for our final effect, we started from the standard surface shader template, which already includes our albedo map, base tint, and smoothness:


The albedo is there, but this hardly looks like a ghost – more like a plastic toy. Let’s add a bit of texture first with our normal map. Shader veterans will be happy to hear that Unity will do all of the tangent-space conversions for us, if you’ve imported your texture with the “Normal Map” texture type selected. All you need to do is use the UnpackNormals function. If you’d like to adjust the intensity of your normal map, just employ one of the worst-kept secrets in computer graphics – multiply the result of your normal map read by a colour with your desired intensity factor plugged into the red and green channels, while leaving the blue channel at 1:

o.Normal = fixed4(_BumpIntensity, _BumpIntensity, 1.0, 1.0)
* UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));

So here’s what Spirit looks like with some detail, because real ghosts have pores (slightly enhanced for demonstration):


The material texture is closer to correct now, but he still looks like a regular plastic object without any glow. Let’s start by adding our emission map, which will make his eyes glow, by simply setting the Emission property of our output structure to read from our emissive texture:


While it’s a little too satanic for our purposes, we’re starting to see a promising glow – unfortunately, when combined with our full-force smooth albedo, which happens to be a bright base colour, the result is less “mischievous ghost” and more “irradiated cyclops”. Let’s fix this by toning down our albedo map with a darker tint colour and letting most of Spirit’s apparent colour come from our rimlight map, which is a toned-down modification of our base colour map. Rimlighting works by comparing the angle of the viewer’s eye (i.e., the camera view direction vector) with the surface of the object (i.e., our final surface normal). We want the edges of the object to glow, meaning that if the two vectors are perpendicular, the glow should be maximized. Therefore, we’ll use the dot product, clamp it, and subtract the result from 1 to give us our base rimlight intensity, which we can then modify using a custom intensity variable, tint colour, and our rimlight map. For our purposes, we’ll add the resulting colour to our emissive output:

half rimTerm = 1.0 - saturate(dot(normalize(IN.viewDir), o.Normal));
o.Emission = tex2D(_EmissiveTex, IN.uv_EmissiveTex)
+ _RimColor * tex2D(_RimTex, IN.uv_RimTex)
* smoothstep(0.0, 1.0, rimTerm * _RimIntensity);

After tweaking the colours to our liking, we’ve got something like this:


Finally, that looks quite a bit more like what we’re going for. Now, for one last feature – our partial alpha. The tricky part here is getting the depth buffer to behave properly. Here’s what happens if we add an alpha slider and flag the shader as transparent using tags:


Ouch. Not what we want at all – we want to be able to see the background through our little guy, but not his disembodied limbs – note the horrible clipping effect that’s happening as well. Resolving this is surprisingly easy – we complete a pre-pass to fill the depth buffer with an empty colour mask, ensuring that our final render will only deal with the bits of the surface closest to the camera, disregarding all that back geometry. Here’s the code for our pre-pass, which is painfully short:

//First pass.
ZWrite On
ColorMask 0
//Set up our next pass.
Cull Back
ZWrite On
Blend SrcAlpha OneMinusSrcAlpha
//CPROGRAM begins here...

Now let’s have a look at the little guy with some stuff behind him:


There we go! While we’ve got some texturing and post-processing tweaks we can make to improve the effect, there’s our surface shader, now with 100% fewer disembodied limbs. For reference, here’s our final list of properties in the surface shader, and the adjustment panel:

_Color ("Color", Color) = (1,1,1,1)
_Alpha ("Base Alpha", Range(0,1)) = 1.0
_MainTex ("Albedo (RGB)", 2D) = "white" {}
_Glossiness ("Smoothness", Range(0,1)) = 0.5
_BumpMap("Normal Map", 2D) = "bump" {}
_BumpIntensity("Normal Intensity", Float) = 1.0
_EmissiveTex("Emission Map", 2D) = "black" {}
_RimColor("Rimlight Color", Color) = (1,1,1,1)
_RimTex("Rimlight Texture", 2D) = "white" {}
_RimIntensity("Rimlight Intensity", Range(0.0, 2.0)) = 0.0


Finally, here’s a family portrait with our old model on the left, with standard shading, and our new and improved shaded model on the right:


And there we have it – our little friend is ready to wreak havoc in style. We’ll be back soon with more updates on Spirit!

Spirit Development Update: July 2017

Now that we’re rounding out our third official month of development, we’d like to take some time to review our progress and share it with the community. It’s been a busy season for us, with lots of business meetings and new opportunities. We’re excited to announce that we are working with Northumberland CDFC to help fund our development efforts and that we will be participating in the UOIT business incubator throughout the year!

Reagarding Spirit, we’ve nearly finished much of the game’s core prototype functionality, having implemented alpha versions of our core mechanics, user interface, input system, save system, and application management. While we’ve got a long way to go in refining our gameplay and fleshing out our level design, it’s been quite rewarding to see the first few pieces come together. In this post, we’ll reflect on everything we’ve done so far, and how we plan to build on our existing foundation for Spirit in the coming months.


Navigation & Camera

Naturally, our first step in development after setting up our basic input & state management (see below) was the integration of basic player navigation. Our case is a bit unusual in this regard since players will be controlling a lot of different objects, so a one-size-fits all solution just doesn’t work for us. We’ve set up a system that lets us define movement controllers for different objects with varying degrees of deviation from standard rigidbody-based or character controller-based motion, which we will expand as we add new player-controlled objects, integrate animations, and improve the feel of our character movement.


We’ve also set up a basic camera system allowing for locked and free-form camera controls, which supports a couple of different modes of operation depending on the object the player is controlling. It’s currently quite similar to the camera in our initial prototype, with some improvements to interpolation and adjustment behaviour. We’ve also developed a simple cutscene system built from our path editor utility, which has allowed us to start thinking about cinematic aspects of the game. Our next goals with the camera will be the integration of some basic physics and location-based constraints to improve gameplay feel and make it easier for the camera to adapt to different level geometries.


Possession & Summoning

Possession is our core mechanic, and so it will be something that is in a constant state of expansion, refinement, and testing throughout the development process. Right now, we have a few different objects in our prototype for players to control (a large, bouncy ball, a marble, and a paper airplane), in addition to Spirit himself. Objects control quite differently depending on their physical properties – shape, size, weight, air resistance, and so on. We’re using three primary controllers at the moment for our current set of objects – a character controller-based model for Spirit, a controller we’ve designed specifically for flight, and a controller for rolling objects (the latter two are both heavily physics-based).


Additionally, we’re integrating our post-processing system with possession to give each object a unique aesthetic when players are “inside” the object, which we’ll be expanding on in later updates. Right now, we’re experimenting with a few different effects related to image warping and colour distortion. No psychedelics have been involved in the process, we promise.

Rescue & Collection

Players’ primary objective in Spirit is to rescue their ghostly cohorts from a devious team of paranormal exterminators, who’ve trapped them for later disposal. Spirit, who managed to evade the exterminators’ dastardly traps, will not stand by and allow innocent poltergeists to suffer in captivity. After all, a little innocent haunting never hurt anyone!

We’re going to be designing a number of different friends for Spirit to rescue, which our artist Josh will be bringing to life shortly (we’re acquiring supplies for the ritual). In the meantime, we’ve integrated the mechanic with a host of adorable magenta ghost clones, which aren’t terrifying at all, thanks to their giant yellow eyes. Ever watching. Staring. Judging.


Players can also collect little bits of concept art, tutorial images, and assorted bits of photographs and the like throughout their adventure, which they’ll be able to visit in a little journal menu, hosting their collection and detailing their current objectives.

Interaction & Dialogue

Once we’ve fleshed out our story and side characters a bit more, we’ll be integrating a fair bit of narrative, sassy conversation, and general tomfoolery to complement the game world. Right now, we’ve prototyped our system for interaction and conversation with a couple of talkative books. We’ve integrated this system with our collection mechanic, so that players can “take” things from NPCs via interaction, and we’ll be adding some basic fetch quests, riddles, and so on in the future.



A new feature we’ve been working on is an ability/talent tree similar to what you might find in an RPG perk system (though far less complicated!) or a game like Ori and the Blind Forest. At the moment, we’ve just finished implementing a skeleton for defining abilities, acquiring perk points, and spending those points to acquire and use abilities. We’ll be working on designing and implementing unique talents over the next few months.


Application Management & State Saving

I like to have the application back-end up and running before taking on almost anything else, so that we can switch between scenes and deal with global GameObjects effectively. This helps us avoid snafus with the inability to test state transitions, getting caught up with persistent objects, and so on. Thus, our app manager was one of the first things we worked on, and we’ve expanded it steadily to accommodate new features as necessary.

We’ve also been extending our save system to support better player data management, improved file handling, and the ability and collection mechanics.


Input was another of our initial areas of focus, as we wanted to develop a custom wrapper for Unity’s input system that allows us to query input based on actions defined outside of Unity’s input manager. We did this so that we can build a system for players to rebind their inputs effectively in-game, rather than having to rely on the Unity launcher. Furthermore, this leaves us the flexibility to import custom input plugins if we want to integrate support for different controllers or improved input polling in the future.

User Interface

Our UI is largely prototypical for now, with many placeholder assets and sprites taken from our older iterations. However, we’ve fleshed out the functionality of the HUD, menus, and hubworld, and we’ve built a solid foundation for our redesign of UI elements, which we’ll be working on soon. We’ve also spent some time wrestling with Unity’s default UI navigation, to ensure the best experience for players using a gamepad.


Animation & Sound

Our path editor has been serving us well, and we plan to use it as a tool to help animate obstacles, characters, and visual effects once we’ve finalized our level designs. We’ll have the all-new Spirit character model and animations within the next few weeks, but for now, we’ve integrated our old animations into Unity’s animation system, with a small bit of customization built on top for our gameplay needs. We’ll be extending this system as we continue to refine our character movement and generate new designs. For now, little old Spirit still looks pretty adorable, though.

We’ve also integrated some of our old sound effects and music, and we’re working on balancing and extending our simple sound system to better handle transitions and the overlay of multiple effects. We’ll also be working with some brand-new editing software and digital instruments soon, so stay tuned for music updates!


What’s Next

Our next major priority is revamping Spirit’s model and animations, and updating our navigation code to ensure a great platforming experience for players. From there, we’ll be refining our core mechanics and working on level design and asset creation, before drilling down into our puzzle design and adding depth to the game. We’re having a great time working on Spirit and we really hope that you’ll enjoy it when the time comes!