So we recently launched a shoot 'em up arcade-type game (think Smash TV or I Made a Game with Zombies in It!). You can move in one direction and fire in another, so the ideal control scheme is probably two analog joysticks (like the Xbox 360 has). We support WASD to move and arrow keys to fire. The best way to control though is to move with WASD and aim with the mouse.
We're getting a lot of people asking for mobile versions of the game (mostly for iPad and Android) and the problem is we just can't come up with a good way to translate the controls over to a touch device.
Interestingly, someone actually hacked an early version of our game a while back to work on Android by overlaying D-pads, and sure enough, it was almost impossible to control. The game gets really difficult later on, and the thought of releasing a game with a crappy control scheme that nobody could possibly ever use to beat the game does not sit well with me.
So I was wondering if anyone has any previous experience or suggestions on how to approach this problem? Overlaying two D-pads on the screen is clearly not the way to go and we're kind of at a loss for other ideas.