iOS falls asleep when not touching screen

This was asked before, but not really answered in a way I can use it.

A game that uses accelerometers only, no screen touch, leads to the iOS device falling asleep while playing the game. Touching the screen helps, but is not user friendly. Preventing sleep totally, is against the rules, since it could drain the battery if someone lays the device down and forget's about it, that's why it's automatically shutting down after a while of not using. But it's used. The user is holding the device for playing the game via the accelerometers. Strangely enough, the demo project roll-a-ball does not seem to make the iOS device fall asleep. Am I missing something? A flag, a line of code, a tip, a trick, a checkmark?