November 6, 2009

iPhone Doom Controller Mod

Doom (by id Software) just recently came out for iPhone. Doom is one of my favorite classic games so I had to download it. The iPhone is definitely a popular platform for games, but First Person Shooters (FPSs) generally don’t work all that well due to not having discrete controls such as mouse/keyboard or joystick and buttons. I have found that I tend to get overwhelmed with multi-touch controls for FPSs.

John Carmack, lead programmer at id, tried some new control schemes to get Doom to work on the iPhone. One interesting approach he implemented is a virtual steering wheel to control the direction the character is facing. I tried it out and found that control mode to be very promising. It worked much better than the virtual joystick approach other iPhone FPSs have used. That is, it worked nicely when I was casually exploring a level. However when things got more hectic, I found it easy to accidentally turn the steering further than intended. This happens when your thumb inadvertently crosses over the axis of rotation and causes a large and disorienting jump in your facing angle.

Doom_steering An image of Doom with steering mode configured.

This problem might be able to be reduced by placing a “dead zone” in the middle of the steering wheel. (I suspect there is already a very small “dead zone” in place.) Along this train of thought, I came up with a little “mod” that sort of fixes the problem. I temporarily stuck one of those no-slip rubber feet that come with various electronics such as external hard drives right in the middle of the virtual steering wheel on my iPhone screen. This created the “dead zone” that I desired, but also gave me a tactile point of reference so that I always have a good idea what might current steering angle is. This significantly improved my performance in the game, but still nowhere close to as well as I can do with keyboard/mouse on a PC.

Doom_steering_nub Doom_steering_num_closeup These two images show my “steering nub” mod

I think similar stick-on barriers could help with other aspects of FPS control too. Although, ultimately I think that certain game genres really need discrete tactile controls.