The first section of the pitch generally addresses the concept of the game and the idea behind it. The concept should be described in a few sentences that allow anyone to quickly grasp the basic mechanics of the game and communicate its look and feel, using little, if any, technical jargon.
When describing the concept, include anything that is necessary to explain the basic gameplay of your title but leave out what relates to special cases, additional contents, and information that may confuse the reader.
If your concept is not brief or very clear and it cannot be grasped with a single reading, it means that you still haven't got a good concept to begin with.
Work on it until you can provide a single, short sentence, usually called high ...