When the screen hasn't been touched for some time it goes black/into sleep mode. The time it takes depends on the settings in the phone. Called Screen timeout (I guess, my phone is not in english though)
Can that be controlled by an app? the timeout period is a timeframe from last time you touched the screen.
But I am playing with a game that you controll with the gyro. you do not have to tap the screen. But then the phone always go black after 30sec since you do not touch the screen... Possible to force it to be awake while in a certain app?