One Switch Gaming
User with the most severe motor impairments, such as spasticity, amyotrophic lateral sclerosis (ALS) and cerebral palsy, may find it difficult or impossible to use a regular controller or a mouse and keyboard to play video games. A switch is an adapted input device which can be operated by any body part that is able to produce consistent and voluntary movement. Different types of switches can be identified based upon the type of action required to use them (sip and puff, pull, push, or squeeze). Users may use a single switch or multiple switches depending on their impairment. The smallest amount of input that can be provided with a switch is a binary input as holding down the switch for a certain amount of time may be impossible for a certain switches such as sip and puff or painful for someone with arthritis.
Playing a mainstream game, such as a first person shooter or real time strategy game, using switch input is often impossible as the amount of input required to play the game goes beyond what can be provided with a switch controller. However, games can be modified to allow for switch access, by reducing the amount of input the user needs to provide.
Switch Game Prototypes
Arcade like games such as pong or pacman have been made switch accessible, but modern mainstream game genres with complex interaction mechanisms lack any switch accessible examples. To gain a better understanding of how to make games accessible several of students have developed a number of one switch access prototypes:
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Match 3 Game
This popular puzzle genre of games has been made popular by the success of Bejeweled. The objective of this game is to swap one gem with an adjacent gem, using mouse clicks to form a horizontal or vertical chain of three or more gems, hence the moniker match 3 games. We implemented a row/column and a polar scanning mechanism to allow the player to swap a gem in three steps. A switch accessible version of bejeweled can be downloaded here (Windows only). You can also watch a video of one switch bejeweled.
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First Person Shooter
First person shooters have been popularized by the success of games like Doom. These games are played from a first person view and require the player to navigate their character using the arrow keys and aim their gun with a mouse or both using a controller. For the multiplayer version of the popular Half life 2 shooter we developed a modification that automates navigation as well as aiming allowing this game to be played with one switch input. Download the modification here. This mod requires a copy of Half life 2. Alternatively take a look at a video of one switch FPS.
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Monkey Ball
Monkey Ball is a popular game involving tilting a platform in such a way that you roll a ball in a certain direction to avoid obstacles and to collect coins. We modified an open source version of this game called Neverball and we made it one switch accessible by applying a two step polar scanning mechanism. Download the one switch version of Neverball here (windows only). |
Strategies for making games switch accessible
Based on our experiences with developing these switch accessible prototype interfaces we identified three different strategies for making games switch accessible:
- Automate: the input that needs to be provided. For example for a first person shooter this can vary from automatically picking up ammo or aiming to automating a user's movement by placing the user on top of a bot.
- Remove: the input that needs to be provided. Instead of automating input one can also leave out functionality. For example in the one switch first person shooter we do not allow the user to switch weapons manually but switch the weapon when the ammo runs out.
- Scanning mechanisms allows the user to provide a larger amount of input at the cost of a slower rate of input. Scanning basically breaks up the interaction of a game into chunks and adds them to a chain. The game will iterate over each element of the chain allowing the user to select the selected input. However it can be tricky to apply this mechanism to time sensitive games and it may also increase the cognitive load. Linear or Row/Column are typical scanning methods for on screen keyboards. For bejewelled and Monkey ball we implemented a rotary scanning mechanism which is faster, though it may be a bit more challenging to select gems on the edge.
The
one-switch website run by my friend Barrie Ellis lists about 70 arcade-style one-switch games, all of which can be downloaded for free.
