Previously we looked at active space as applied to chess pieces.
It was mentioned how the presence of another game element can impact on the active space available to the player, in the form of the interaction between a rook and pawn, as follows:
With the pawn in its path, the rook’s available active space is affected; this particular piece has less of the playfield with which it can have an effect. In gameplay terms, less active space can affect a player’s interactions in very real ways. Let us consider Space Invaders.
The default active space for the player is thus; the ship can move left and right, or can fire upwards. It logically follows that active space encompasses the limits of both the ship’s left/right movement but also the extent of shots, vertically – if the shots encounter an obstacle or enemy, since they do not pass through, the active space is limited to the space they shall occupy.
The bases or shields in Space Invaders serve to protect the player ship from attack, but their effect is twofold — they seriously impede the player’s vertical reach and thus the active space available to the player.
These shields can be shot-through to afford the player more vertical active space. As also demonstrated here, the shots will travel between invaders at this moment in time, which may miss the invaders themselves but could potentially hit one of the bonus UFOs that fly at the top of the screen.
Obstacles that impede a player’s active space are core to gameplay at the most basic and fundamental level. As a designer, controlling this amount of space can open up potential avenues of strategy (as shooting through bases in Space Invaders can offer a little less cover in exchange for opening up the active space they otherwise deny) as well as make the experience more or less of a challenge at the most basic level; a simple rule of thumb (though exceptions apply, as always) is that more space available to the player equals an easier game, and the inverse of this.
Active space is the way in which a player directly interacts with a game at any given moment. Change this, and interactions change to follow.