- The targets.
- The attacking pieces.
- The roadmap with the roads across which the attacking pieces get access to the targets.
This sheds new light on an old question about steerability of a game. The roadmap is determined by the pawns. If there are no pawns, no road is blocked and you can move your pieces freely across the board. The amount of open roads has a great influence on the amount of possible moves (of the pieces, we are talking about here) hence at the complexity of the game. Have a look at the following position of a game of Margriet.
White to play exd5 or e5.
Of course there are other and better moves than exd5 or e5 here. But that is not what I am investigating at this moment.
1. exd5 opens up the game and adds complexity. If black is a better calculator than white then his chances increase, allthough he is still worse, of course. It makes the game more of a gamble.
With 1. e5 more roads are, or continue to be, blocked. But is has another advantage in stead, it gains space. And hence manoeuvrability. The manoeuvrability of black is diminished while that of white has improved. This means that your chances have increased.