Multiplayer maps are also a notable exception to this rule. Figure 29 is an example of a deathmatch type space that purposely prevents the player from being able to close off spaces. This type of spatial design is intended to be strictly non-linear, and force confrontation as much as possible.
Just as planar objects affect the metrics of space, so to do height elements. Earlier in the article, we considered how gantries could be used as an advanced type of occluder, allowing the player to gain an advantage as they have greater situational awareness.
It is also important to once again demonstrate how line of sight takes priority over virtual space in terms of metrics that determine difficulty.
Although the player will have limited evasion vectors, a gantry like the one depicted in Figure 30 will give the player strafing abilities whilst they are targeting enemies on the lower floor. The combination of these two elements combined give the player the most advantageous position in this scenario.
To demonstrate this point even further, let us consider the player in the inverse position. Whilst close to the gantry ledge, the player will have a significantly occluded view of the position above them. Further to this, the only way they have of removing this occlusion is to backpedal. As demonstrated in earlier examples, if the player is backpedaling away from the gantry, any enemy attempting to target them will require fewer correct cycles to gain an accurate hit.
To demonstrate this point even further, let us consider the player in the inverse position (Figure 31). Whilst close to the gantry ledge, the player will have a significantly occluded view of the position above them. Further to this, the only way they have of removing this occlusion to backpedal. As demonstrated in earlier examples, if the player is backpedaling away from the gantry, any enemy attempting to target them will require fewer correct cycles to gain an accurate hit.
The player in this scenario takes a risk by undertaking a backpedaling action to engage a potential enemy that is higher than them (Figure 32). Although the eventual outcome will mean that an enemy occupying the ledge gantry will be contained within their view frustum, the player is also making himself or herself an easier target. Ideally, advanced players will begin to learn that any backpedaling in this type of scenario should also be accompanied by large amounts of random strafing movements.
The most difficult iteration of this scenario can be seen in Figure 33. If we remove the player's ability to strafe and also add an overhanging ledge over the player's path, then this represents the most difficult iteration of the space. The player has reduced line of sight, hence they are less able to gain situational awareness and plan their actions and possible alternatives. Further to this, the player has had their evasion options compromised in the worst possible way -- they only have the possibility for backpedaling rather than the more effective strafing type movements.
If we find that the example given in Figure 33 is too difficult for the player, we can use rational approach to start modifying the level geometry in such a way that we incrementally reduce difficulty. For example, Figure 34 makes the height of the corridor much higher, so that the player can see that there is a gantry ahead of them. This, then, at least lets them know of a potential hazard on this approach vector and they can then adjust their view frustum to accommodate this portion of the environment as they approach, instead of being forced to add multiple correction cycles.
The term "conclusion" is misleading; in terms of understanding the impacts of space on difficulty and player psychology, what is presented here is merely the tip of the iceberg. The next step in understanding virtual space is to consider that within game geometries, we have a number of attractive and repulsive forces. I have previously discussed the theoretical components of this in another article, which deals with the notion of compression and funneling, and I have hinted at its benefits throughout this article.
Understanding dynamic relationships is the next piece of the puzzle. We need to understand the dynamic forces that compel the player to move and engage with the level geometries. For now, though, this rational approach to difficulty ramping in 3D FPS games can be easily applied to your own design concepts. If spaces are designed with the player's situational awareness in mind, then we can begin to incorporate other design tools, such as Jesse Schell's interest curves, to further improve our designs.
Tan, D. S., Czerwinski, M. P., Robertson, G. G. (2006). Large Displays Enhance Optical Flow Cues and Narrow the Gender Gap in 3-D Virtual Navigation. Human Factors: The Journal of the Human Factors and Ergonomics Society Summer 2006 vol. 48 no. 2 318-333