No offence to you, but why are you using ZBrush at all at this stage? If your looking to create game assets I suggest you leave ZBrush alone and concentrate on low poly modeling in Maya.
Trying to learn ZBrush and maya at the same time when you don't know ether will be a frustrating and very very long process.
Dave 
From a readers' Q and A column in TV GUIDE: "If we get involved in a nuclear war, would the electromagnetic pulses from exploding bombs damage my videotapes?"