I’ve been spending a bit of time experimenting with some game concepts on iPhone, and how a touch screen input system effects them. In some cases I’m impressed how well certain input schemes work with it, and with others I’m surprised how poorly they work.
When holding the iPhone in landscape mode with two hands your thumbs are free to tap and slide the touch surface. Sliding movements on the touch screen work very well–especially up/down gestures. One concept I was toying with mimicked a trackball and it had a great hand-eye correlation between sliding and the result on screen. Tapping the touch screen with your thumbs starts to break down when you’re required to tap with any amount of precision. Without tactile feedback I find it easy for my thumbs to drift unless I’m looking directly at what I’m supposed to tap. Games with more than one button per thumb (i.e. two buttons) become challenging after a while.
My experiments really hit home for me how critical tactile feedback is for a game. The game is on the screen, but it’s played with your fingers. With a game controller or keyboard or mouse, your brain instructs your fingers what to do. Your nerve endings report back what was performed. Your eyes register the game’s response to the input. Your brain is then delighted or disappointed with the outcome.
With a game controller, if your brain is disappointed by an outcome in the game, it can evaluate the response against the signal sent back by your nerve endings based on what your fingers performed. Your brain can then adjust what your fingers perform for next time. But without tactile feedback, the only information your brain gets back is timing information. The sensation of hitting the left side of the d-pad isn’t there. The pressure felt from the right analog shoulder button is missing. All your brain knows is when it touched the screen. A lot of the subtle feedback you get from playing a video game is missing, and thus at a very low level it’s difficult to derive enjoyment from playing a game on a touch screen.
This is partly why sliding movements work so well… As with a trackball, the surface of the trackball pretty much feels the same the entire time you’re playing it. The feedback you get when sliding on the screen is in the acceleration/deceleration of your entire thumb and part of your wrist–not just a finger–so it registers louder with your brain than a tap does.
Overall, I don’t think touch screens are the “next” big thing in gaming. I’m open to new ideas, but today, I remain unconvinced…
And while we’re on iPhone… I’m totally unconvinced of the usefulness of the accelerometer for gaming. I’m yet to see a good use of it and I haven’t had any success with it myself. First, you have the same issue with tactile feedback. The iPhone isn’t very weighty so it’s hard to feel precisely how it’s oriented in your hand(s). Second, the accelerometer feels kinda laggy. It might take the software a while to process the data.. (?) Third, the accelerometer is attached to the screen! You can’t make any interesting movements with it without preventing yourself from viewing the screen.