Input Structures

Once I had my screen laid out, I set to work figuring out how the user could control the power plant. Having gotten the problem backward by laying out the screen before settling on my input structure, I was now in a bind. I could figure no clean way to control the power plant with a joystick and cursor. Being young and impatient, I simply barged through the problem with a wretched solution. The game offered eight controllable devices: four pumps (the orange octagons), three valves (the orange X-shaped objects), and the reactor core. Clearly the player would somehow use the joystick to select one of those eight objects, press down the joystick button, and actuate the joystick up or down to adjust the device. But how, exactly, should the joystick select one of the control devices?

This may seem a ridiculous question to a generation raised on mice. Put the cursor on it and click, right? Not so fast, young-un. Back in those days, we didn't have mice, and we didn't use cursors much except for maneuvering through text. Moreover, joysticks are nowhere near as handy as mice for moving cursors around on the screen. I considered using the joystick to move a cursor, but decided that users would find the experience uncomfortable. We didn't have standard conventions for what a user could click on. It seemed likely that the user would scroll around the screen randomly clicking on things that didn't do anything, growing ever more frustrated. I therefore decided to implement a "jumping cursor" as opposed to the "sliding cursor" that is the standard nowadays. My jumping cursor would have only eight possible positions to occupy: one for each controllable device. A single step of joystick movement would jump the cursor from device to device. It was clean and simple, but fatally flawed.

Look again at the screen display. The eight controllable devices are not laid out on a clean rectgrid. Moving from one to another requires horizontal movement in some cases, vertical movement in others, and diagonal movement in still other cases. How was the player to know how to get from the auxiliary feedwater pump to the reactor control rods?

My design simply papered over this problem; I cobbled together a table of jump destinations. When the player used the joystick, the cursor jumped to the location that seemed best. The spatial fidelity of the system was cockeyed, but people were so unfamiliar with cursor-control systems that they didn't seem to mind. In short, I fudged the problem and got away with it.



Chris Crawford on Game Design
Chris Crawford on Game Design
ISBN: 0131460994
EAN: 2147483647
Year: 2006
Pages: 248

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