Height variation in track design fulfills two distinct purposes. The first is to create asymmetric balance which may favor or disadvantage certain types of vehicles and the second is to create tension, relief and the occasional "vista moment". The latter of these two purposes is a topic in itself, and one that I have previously discussed in some detail in another article. However, to concisely summarize the two uses, we can consider that the first plays a game design role, which will either advantage or disadvantage certain vehicles based on their mass and power.
To paraphrase the later use, we can consider it to be a purely emotional component of both track design and level design in general. Limited line of sight will result in the player being anxious, as they are less able to plan ahead. When the player has increased line of sight, they feel empowered, as they are able to easily plan their moves several steps in advance. The previous article expands this concept in some depth.
From an emotional perspective, height variation makes tracks interesting, so long as it is used in moderation. Height variation can also be used to create "vista moments" for the player that add that extra wow-factor to the environment and the play experience.
These vista moments are usually achieved by restricting the player's line of sight for an extended period by forcing them to travel up hill.
Once they reach the plateau and begin their subsequent downhill run, their line of sight is increased significant in comparison to the uphill run, allowing them take in a full view of the circuit and the level art. Once again, as this is such a significant topic, it is best to use the previous article as a starting point to investigate the concept further.
Now that we have an understanding of the metrics of track design, it is time to apply these in the contexts of the two case studies. However as vehicle dynamics plays such a key role in understanding the design of racing games, it is necessary to differentiate Initial D and Maximum Tune by examining the types of vehicle dynamics that they use. Maximum Tune favors a type of driving called the "Scandinavian Flick", whilst Initial D is characterized by a system which can be defined as "Race Line Punishment".
Figure 14 is an example of how the Scandinavian Flick works. The player hits the ideal entry point and then turns the vehicle towards the ideal clipping point.
Once the vehicle's mass is heading towards this point, the player then counter-steers and aims the vehicle towards the ideal corner exit, eventually countering the vehicle's inertia and transitioning the mass of the vehicle towards a different point in space using a combination of longitudinal force, lateral force and yaw. It is the excessive amount of longitudinal force used in the Scandinavian flick which differentiates itself from pure 'grip' forms of driving.
Earlier in this article, it was mentioned that lateral force is detrimental; however, the vehicle dynamics in Maximum Tune have been designed in such a way that small portions of lateral force are actually required for the ideal race line.
In the case of Maximum Tune, the vehicle will lose speed on the turn in, but will gain speed on the counter-steer. What this means is, in Maximum Tune, it is often more desirable to spend more time in counter-steer -- and this subsequently means that in Maximum Tune most of the ideal clipping points are less than 50 percent of the way through a corner.
This is one of ways in which Maximum Tune addresses the issue of lateral force being detrimental. By having the clipping points earlier, it means that the majority of the corner is spent apply more longitudinal force than lateral force. Maximum Tune is able to make clipping points come earlier, by making the corner exits wider than the entries.
Both Maximum Tune and Initial D use missed clipping points as a way to punish players and provide overtaking opportunities. Figure 15 is an example of a player who has missed the ideal clipping point. In order to maintain the race line (and block the fastest possible way through a corner) the player will need to make a further correction, hence slowing the vehicle down unnecessarily.
A vehicle does not like to be disturbed by unexpected forces once in motion. Every time a correction is required, this places some extra and unexpected force of the vehicle, subsequently slowing it down or making its behavior erratic. In all racing games, a high corner exit speed is always the most desirable outcome for the player. These examples will be further expanded upon when examining the case studies.
Initial D uses a system of vehicle dynamics which combines slip and grip vehicles and subsequently creates an asymmetrical relationship between vehicles -- vehicles do not need plastic symmetry, as the combination of the player and the track will always create asymmetry.
Some will be more inclined to use Scandinavian Flick, whilst others will be pure grip, race-line vehicles, taking the most effective line through a corner. This asymmetric relationship means that the primary mechanic in Initial D is race-line punishment.
Figure 16 is a time-lapse example of two vehicles entering the same corner. The silver vehicle takes a less risky race line, however it opens itself up to being overtaken on the inside using the more risky, but subsequently more effective, race line. As the red vehicle is able to hit the ideal clipping point, it will yield a higher corner exit speed. The CX values of the vehicles (a measure of how much energy they absorb in the case of a collision) means that the red vehicle has the advantage in Initial D, as its mass will push the silver car off the ideal race line.
In both Initial D and Maximum Tune, the player needs to weigh up how they will approach the corners. Figure 17 is an example of player who takes less risk by allowing greater room for correction on either side of the vehicle. Although they are less likely to hit the sides of the road (and subsequently lose la significant amount of speed) they are also taking a less effective race line and subsequently allowing room to be overtaken on the ideal race line.
By taking the most risky line through the corner as seen in Figure 18, the player has the most to gain if they hit the ideal clipping point, but also the most to lose if they fail, due to the lack of correction space.
Generally speaking, when vehicles in a racing game collide with each other, they impose less inertial forces than hitting a track barricade. What this means in relation to driving games is it is more beneficial to hit another vehicle as opposed to any other obstacle, as the player will ultimately be able to maintain a higher level of vehicle stability. When the vehicle is more stable, it is more likely to accelerate quicker and corner more predictably as there are no other forces acting on the vehicle's dynamics.