I've done a little bit of music-type audio engineering, but nothing for games. But my 2 cents would be simply to get a decent USB condenser type microphone.. I think you can get one for around $50 now. and use a program called Audacity, which is free, to record and clean up your recordings. I also imagine that the engine uses some sort of environmental audio system for a realistic effect. so I wouldn't overdue the effects in Audacity before bringing it into the engine. Hope this helps!