Glad to see you further working out the design! (future Rathalos here: seems like in the end this boiled down to a lot of disagreements on the design, but it’s all constructively intentioned!)
Mass
- More Mass increases Cold Tolerance, Decreases Heat Tolerance.
- Less Mass increases Heat Tolerance, Decreases Cold Tolerance.
SA:V
- A Higher SA:V Ratio Increases Heat Tolerance, Decreases Cold Tolerance.
- A Lower SA:V Ratio Increases Cold Tolerance, Decreases Heat Tolerance.
My first thought is: Mass and SA:V here have exactly opposite effects, and due to square/cube law larger mass automatically means lower SA:V (unless you change shape to compensate). Since they move in the same direction, it seems simpler to discard mass effects and focus just on SA:V, unless the effects specifically scale at different rates?
(On a side note, the mass effect in this later statement:
Mass effects and SA:V effects counter-act each other. Low mass means less heat tolerance while high SA:V means high heat tolerance, and v.v for cold tolerance.
Seems incorrect and inconsistent with the earlier statement?)
From a realism perspective also, more mass typically means more living tissue which does mean more heat from metabolism. But while an organism of exactly double the mass would produce double the heat, it is spread out over double the mass, making the resulting temperature the same… Assuming the SA:V ratio is more or less the same (for example, it’s a centipede that just became twice as long) then total SA is double, so it’s also losing heat twice as fast, and there’s no nett difference in temperature tolerance.
I think both of these point towards saying for temperature effects we can look at just SA:V.
I do think for SA:V effects you’re mostly in the right direction. The critical physical fact is that living metabolism as we know it will only ever produce heat, never consume it. So every living thing would eventually cook itself if it wasn’t losing heat to the environment. That loss is slower if the environment is hotter, and is sped up the larger the volume is, hence as you said:
A Higher SA:V Ratio Increases Heat Tolerance
Similarly, if you want to retain heat to defend yourself against the cold, having less surface area will reduce that, so:
A Lower SA:V Ratio Increases Cold Tolerance
There is a complication here though:
A Dimetrodon, who’s sail might have been useful in regulating temperatures.
The trick with sail-like structures (also from what we know from animals today) is that they indeed by default increase heat loss, but by correctly angling them to catch the sun, they can also absorb more heat. (external heat being the second source of heat besides metabolism).
But I think this kind of specific behaviour/mechanism we can leave for later discussion outside the “fundamentals” we’re discussing here.
I also want to point something regarding what you say later:
One problem that can come up is that since the player starts as a puny macroscopic animal, they will inherently have a really high SA:V
I would actually phrase this in a more extreme way. The smallest possible Macroscopic design, a single tiny metaball, is the absolute highest SA:V possible. That’s the maximum. Growing the metaball or adding more immediately starts dropping SA:V. S o the entire rest of the time in Macroscopic/Aware if you grow in size as a player you are always moving towards:
You can only change shape and add special structures to essentially “limit the trend.” Again, square/cube law says you should always expect SA/V to drop as you grow larger.
A third-ish point: the idea that at a small size cold temperatures are hard to survive is a bit Endotherm-centric. As mammals we are burning energy to keep our body temperature constant and being small gives a large SA/V, thus dramatically increasing how much heat we lose. If the temperature is too low, we just die, same as if the temperature is too high.
We’re Thrive, though, so we also want to think of Ectotherms. If you’re not trying to maintain your temperature, then, like insects, lizards, etc. you just live at whatever the ambient temperature is, and your cell/tissues need to be built to handle whatever that is. Too hot temperatures will cook them (but unlike endotherms, they’re not producing heat so this is much harder to reach), while cold temperatures just slow them down, except if the temperature is really extremely low and they actually freeze to death. SA/V still plays a role here though, really large ectotherms will retain more heat and therefore activity in the cold. (I presume this also makes them more likely to overheat)
Scaling Concerns
Taking everything I said before together, I think I have a counter-proposal that also fixes the scaling concerns:
(assuming temperature tolerance works more or less as it does now in Thrive)
- We look only at SA/V.
- Decreasing SA/V increases Cold Tolerance and decreases Heat Tolerance. (But perhaps increases Cold Tolerance more than it decreases Heat Tolerance?
- SA/V at its maximum value (the tiniest metaball) has 0 effect, so temperature tolerance is equivalent to the cell’s temperature tolerance / the temperature tolerance the Multicellular Species had. So the SA/V value can only push in the direction of the previous bullet point.
- The overall effect is very small by default. It should be significant on the scale of real-life gigantotherms such as leatherback turtles. There will probably need to be some more in-depth discussion on what exactly the right mathematical scaling is.
- Becoming Endothermic (this can be a smooth transition, btw) simultaneously makes the SA/V effect much stronger and worsens the default cold tolerance by a lot. (at the right size, cold tolerance essentially does not change) So, suddenly being too small is a lot worse for your cold tolerance, but you can potentially have better cold tolerance than the ectotherms. (endothermy would also have other benefits)
Am I making any sense?
As I alluded to before, we also want to consider how temperature tolerance should work at all in Macroscopic. For example, our current maximum temperature tolerance is rather high and not so believable for complex life, as I think you also realised:
A feature to consider is to have environmental tolerance ranges shrink as mass increases, thus making it a problem that larger, more “advanced” animals will have to deal with.
Setting your tolerance to maximum also does not have any downsides (other than compared to the complete other extreme of being temperature-specialized) which is a problem I have pointed out before.
More significantly, this system where you have to be mindful of your shape to regulate temperature does not seem very compatible with current temperature tolerance mechanics, where you can just easily set your ideal temperature via slider to whatever you want anyways. So I think you already had other ideas?
DEEP DIVE ON GROUND MOVEMENT AND INTERACTION WITH CONSTRAINTS
I think this is a great improvement over the earlier more vague statement! I do still have some comments though.
What Affects Land Mobility?
Speed will first of all be heavily influenced by mass of the body, not just the limb itself.
- More massive organisms will generally be less fast and less agile.
- Less massive organisms will generally be faster and more agile.
I only agree with this in terms of “more mass with the same amount of propulsion moves slower.” But in practise more muscled and (especially) longer legs offer more “propulsion” so the end result is that more massive organisms tend to be faster in absolute terms.
I do think it is more accurate for agility, but also not as much as you would expect. (again, more rotational force)
It’s probably worth also taking some time to think about the difference between “absolute speed” and “speed compared to body size” in each context. A giraffe, a human and a cow all will outrun an ant.
Overall, I think there might be a slight over-reliance on “streamline” here? I think realistically and “believably” streamline should really only be about resistance to your movement from the environmental medium. So, it gets more important as your total speed is higher, and is much more influential in water. I think so far we’re pretty much in agreement? Take those two in combination, and while for birds in the air at high speed streamline matters a lot, for a human walking air resistance (and therefore need for streamline) is pretty negligible. You might have already intended that, but I do not see it clearly in your design I think.
More Streamlined Land Animals
- Have less stamina.
I don’t think this should be an effect of streamline. This sounds like something that should directly come from traits like muscle amount and type, circulatory and respiratory systems, etc.
A more streamlined animal moving through rough terrain should be losing less stamina though.
- Are more capable at maneuvering through rough terrain, swimming, and burrowing.
Fully agree here.
Are more influenced by the effect of mass on movement speed.
Because more non-streamlined mass offers more resistance? That makes sense, though again at relatively low speed on non-rough terrain this effect should be negligible.
This is meant to proximately represent more “squatted”, reptilian leg structures, vs more “upright”, “active” leg structures. More squatted organisms are capable of intense spurts of athleticism and are generally more maneuverable in harsh conditions, but are less efficient overall due to their musculature having to be more involved. As such, they tend to have a tougher time moving on land if they become larger. An “extreme example are crocodilians - extremely well-adapted for swimming and movement on uneven footing, but rather uncomfortable on land.
More upright animals are more efficient movement wise because their bone structure takes more of the energy and force needed to propel themselves. As such, larger organisms tend to have more upright leg structures to maintain movement efficiency. However, longer limbs can be more gauntly. An extreme example are giraffes - among the fastest animals in Africa despite their size, but extremely delicate to uneven terrain.
I see what you’re doing here, but I think lumping this all into “streamline” is not a good idea. Putting sails on your legs makes you less streamlined, but by this system would automatically give you more stamina?
Also, the difference you’re trying to make here sounds more like the difference between a wide base of support versus the benefits of having the legs directly underneath. I feel like that works better as a direct “stat” of the limb, rather than being translated into a “streamline” value? Assessing streamline feels like it would pull in too many things not related to the function of the limbs.
I would strongly recommend we move towards a system where land speed (relative to body size) is determined by overall mass of the animal compared to the length and muscle mass of the legs.
Extremities
I think the effects of the extremities overall makes sense to me. Particularly the interaction between effects on constraints, and having their own effects tied to constraints.
And from earlier:
- “Rough Terrain Movement”, indicating movement through a medium that an organism isn’t suited for. Right now, I think there is a case for just two big groups of rough terrain:
- Boggish/Swampy/Wading Movement - Movement around shallow water. This is important for Thrive because of the progression from living in water to living on land.
- Slope Movement - Movement along terrain which is uneven, such as hilly, mountainous, rugged terrain.
There doesn’t really have to be too much difference between the two “rough terrains” - all that matters is that it slows down base movement.
I would argue that there is significant difference between the two: for the first, streamline of the limb actually does matter. Better streamlining offers less resistance (same goes for moving through brush). For moving up slopes, I think it would not?