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A Guide To iOS Twin Stick Shooter Usability

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A Guide To iOS Twin Stick Shooter Usability

March 30, 2011 Article Start Page 1 of 4 Next
 

[Graham McAllister, director of user experience studio Vertical Slice, examines the conundrum of creating a twin stick shooter for the touch-only iOS, breaking down the dos and don'ts, and examining a number of popular games to see what approaches work best.]

What is a Twin Stick Shooter?

Twin stick shooters are a genre of game which use two controls, typically operated by the thumbs. One control dictates the character's movement, the other the direction of shooting.

Importantly, these can be operated independently, i.e. it's possible to move in one direction, and shoot in another.

The camera angle in these games is either from directly overhead, or overhead and from a slight angle. The games are essentially 2D, i.e. there is no forward (or z-axis) movement.

Control Layout

Movement is almost always on the left-hand side, shooting on the right; some games allow the options to switch this for lefties. This layout is also consistent with twin stick shooters on Xbox 360 and PS3.

Minigore on iPhone introduces the controls very clearly.

All Games are Not Equal

With only two touch screen controls to implement, you may think that all twin stick shooters are created equal, however it turns out that subtle changes in design can greatly affect the player experience.

Terminology

No standard definitions exist to describe the interactions we're about to introduce, so we'll try to keep them as descriptive as possible.

Most of the terminology will be defined when we introduce the four components, however they all have one feature in common, the virtual joystick region (VJR hereafter).

Within this region, thumb contact is registered as control input, if the player's thumb touches the screen outside of this area, it is not registered as player input.

The Four Components

There are four main design decisions to consider when implementing the controls for your iOS twin stick shooter.

  1. Static or dynamic controls
  2. Controls always visible
  3. Controls active outside the VJR
  4. Play to border

These four components are combined to form alternative control implementations.

Before we take a look at the main varieties and show examples of games which use each particular combination, let's describe the four components.

For clarity, our examples will focus on the movement control, but all comments apply to the shooting control also. Each component is really a design decision with two options, so we'll cover each alternative.

Component 1: Static or Dynamic Controls

Static Controls. This approach fixes the location of the touch controls, typically they'll be within easy thumb reach of the corners of the iOS device.

Later we'll see how component three, Controls Active Outside The VJR, extends the usability of the static control approach.


Static controls - fixed at corners of the device.

Dynamic Controls. This approach centers the controls at the point where the player touches the screen, i.e. the controls can change spatial location depending on where the player's thumb makes contact.

Crucially, however, there is one important factor in how dynamic controls are implemented, which brings us on to the second component.


Dynamic controls - controls center where the player taps.


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Comments


Soren Nowak
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Thank you for this excellent article! Rarely have I seen anything that can be evaluated and applied as easily as this.



I wonder how well this translates to first person shooter controls.

Skip McGee
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Excellent writeup, thank you! You do an excellent job breaking down a complicated design problem.



P.S. As a user, I hate these controls with a fiery passion and refuse to play any game that has them.

M C
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Agreed, great article that really captures the evolution of the virtual d-pad.

But when purchasing an iOS game my decision process always starts with: If (game uses virtual d-pad/sticks) Then (pass)



:D

Craig Timpany
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Ugh, virtual joysticks. This is a well-researched set of best practices for a worst practice.



The reason that placing the center of the stick dynamically is important is because the player's attention is focused on the play area, not the control area. They can't see the visuals, so they're getting no indication of where that center lies. This also means they can't recenter the stick except by trial and error.



Have you played Silverfish? Its method is slightly less awful than virtual sticks. Silverfish uses isolated swipes to change direction. If you don't know how to recenter the stick, why bother having a center to return to?



Admittedly Silverfish is pure movement control (ala pacifism), and it's locked to 90 degree angles. I could imagine it generalising to two sticks, so long as the action on screen is kept centered. Forget-me-not also uses a similar system, though the feel isn't as good.

Patrick Dugan
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I agree its a crutch to try importing PS1 control schemes to multi-touch out of generic force of habit, though if done well it's probably good for something.

Kailas Dierk
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Great article, I totally agree with your conclusion.



One thing that wasn't really looked at though was how to control when to shoot (in a game where you can't always be shooting). With both thumbs occupied on the screen as move and aim and nothing remotely comfortable that you can do to get your other fingers on the screen at the same time, I can't really think of another control that can be used?

Vin St John
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In these games, any input on the right thumbstick is generally 'shoot in this direction' input.

Jimmy Baird
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If you have to invest this much time into making ergonomic V-Pads, you should probably re-think your entire controls in the first place.

Maurício Gomes
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Or buy a platform that has buttons... :D



I had a job before and now again my job is design and code for iPhone... But I have no intention of buying one ever, it greatly bothers me the lack of buttons.

Robert C.
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If you want to make a twin stick shooter, make it for a platform with twin sticks. If you want to make an iOS game, create something that makes sense for that platform. While it's true that there are some games that have made virtual sticks tolerable, I do not believe that they will every be good.

Luis Guimaraes
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This.

bunnyhero AKA wayne a lee
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I appreciate the depth of the writeup, but do you have evidence to back up your evaluations? As far as I can tell the only evidence provided is the appearance of negative review comments on one of the games. I'm not necessarily disagreeing with your conclusions, but I would be interested in seeing if there is any objective data beyond one's own personal preferences.

Rob Allegretti
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Excellent writeup and tips, but no reason it needs to be exclusively on the iOS platform. Galaxy and Xoom tabs should be able to use these nicely as well.

Thomas Buscaglia
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This is a decent article, but I have no idea what you mean by camera shudder. If you're implying that using static controls can lead to camera movement interpolation issues, that's absolute nonsense. Sounds like some bias based on one game and lack of sufficient research to me, to be honest. You can play Age of Zombies with static joystick positions and there's no camera shudder at all, obviously. I can't play Revolt because it crashes instantly on my phone, so could someone please explain what this guy is talking about? The fact that it crashes probably has more to do with the ratings than the control scheme.



Also, this article fails to mention a hugely important component of user interface on touch devices which is muscle memory. Static controls allow you to develop muscle memory as to where the different parts of the joystick are. You can, for example, just press down with a tap and hold with a static joystick - something you CAN NOT do with a dynamically positioned one.



I also disagree that the ideal control scheme allows the user to press down in a location that will not allow them to move in certain directions. This article describes the ideal border case handling implementation as one where you can tap at the edge of the screen and then be unable to move in the direction of the edge of the screen you tapped next to. Yet another problem you don't have with static control placement.



"Now, we're not saying that this is a hard and fast rule, but you'd need to have some pretty good reasons to not design your twin stick shooter with this component combination."



This is ridiculous. One solution is not best for all games and dynamic controls have some serious drawbacks that aren't discussed here.

Brad Borne
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I think most telling about twin stick shooters on iOS is that Tilt To Live is by far the best. Which features, well, no 'twin' and no 'sticks.'



One game's limitation is another game's feature.

John Popadiuk
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Also the ability to "swap" controls for players might work well. Unorthodox play should be supported.



John Popadiuk

Creator of Pinball Wizard!

Zidware Studios, Chicago

Dennis Dionne
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You have got to be kidding! I LOVE geometry wars, the version on Wii is probably the best platform for it IMHO, but the version on the Ipad is anything but divine... you can't see half the enemies because you hands are always in the way and i am constantly having to adjust the joystick to see those enemies hidden under my hands... I really tried to like this game because geometry wars is such a great game but the controls were way to awkward on the ipad.



IMO, if you want to make a virtual joystick for you iOS game you should maybe think about a different platform first... maybe one that uses actual joystick...

Bud Leiser
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Best article ever.....if like me your working on a dual stick (twin stick) game.

Also great idea John! I always prefer my move controls left and aim controls right. I hate some PC games that make you use the arrow keys instead of WASD. But I completely forgot about the people who might be the reverse! I remember watching people at the arcade crisscross their wrists at fighting games so the move stick was in their right hand.

Why do people "hate on" developers for making a twin stick game for a device that does not have...sticks. It's a much better control scheme than any of that tilt junk. And more importantly people enjoy it. They take their iDevices everywhere. It's the same reason we have Cameras on phones... convenience for the user, not perfectionism for the maker. Should we only put camera lenses on bonafide high quality cameras? What a narrow concept.

Bud Leiser
Creator of Cursed MECH
KS: http://www.kickstarter.com/projects/budleiser/web-and-ios-game-tw
in-stick-shooter-tower-defense
Just A Game Studio, Vietnam


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