Traveller Heresy - World Classifications
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Author:  Cyborg IM1 [ Tue Nov 28, 2017 10:21 pm ]
Post subject:  Traveller Heresy - World Classifications


As part of my Cepheus expanded world generation, I am trying to build a system that is TOP DOWN, starting with a UWP and moving out and up.

One thing I am considering is a simple roll for non-mainworlds that can be used to easily classify worlds (planets and moons) in a planetary system without requiring a Referee to roll up UWPs for everything.

Traveller already allows GG (LGG and SGG) as a classification rather than a UWP. Other systems use "Rock Ball" "Ice Ball" "Hell World" and even the horrible "Forest World" or "Desert World".

I was thinking about defining a Traveller world broadly by SIZE as follows:
These worlds are large enough to be appromimately round (hydrostatic equilibrium) but not a SIZ 1 world (less than 1600km diameter)

SMALL world (SIZ 1-6)
Most of these worlds have little or no atmosphere and rarely have a hydrographic rating above 0 or 1. In the Outer Zone, denser atmospheres are possible. Good for mining, but rarely are these types of worlds truly habitable.

LARGE world (SIZ 7-12)
These worlds typically have decent, even very dense atmospheres. Habitable worlds are at the smaller end of this range, but these worlds also include Panthellassic worlds and "super-Earths".

GIANT worlds (LGG, MGG, SGG)
Gas Giants of sizes up to Brown Dwarf

This system allows me to quickly create a planetary system (including large moons) and then if anything looks interesting, the Referee can roll up a full UWP with appropriate modifiers for Inner and Outer zone worlds.

Will this fly with the general Traveller buyer? Most seem to LOVE their UWPs, but do we really need them for every planet, every moon in every system, when they will almost never be visited.

Notice that MAINWORLDS is not a size category - mainworlds are rolled FIRST, so would never appear in this system for secondary worlds.

Author:  thrash [ Wed Nov 29, 2017 1:33 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

I've been arguing for something of the sort since GT: First In came out (c. 2000). You should spend your worldbuilding effort on main worlds, not on filler. This is especially true for inhospitable worlds: if your characters are in vaccsuits anyway, does it really matter if the world is also Freezing or Desert?

One thing to keep in mind with a secondary world generation system is that -- statistically, anyway -- the resulting secondary worlds should not be better suited to development than the main world. If your main world is an airless rockball planetoid, but you generate a large secondary world with a decent atmosphere next door, it's hard to justify why the former is the main instead of the latter. Yes, you can always find a reason, but it gets tiresome and trite after the third or fifth or tenth time you have to do so. A system should take care of the majority of cases routinely and let you reserve your creative energies for the special exceptions you want to add.

Author:  Cyborg IM1 [ Wed Nov 29, 2017 2:10 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

Thanks for the feedback and yes, keeping the mainworld as the most hospitable is one of the things I am struggling with.

Take our solar system for example. If Earth was gone and Luna was the planet in this orbit, what would be the Mainworld of this system? An airless rockball in the middle of the habitable zone or a small, cold world near the outer edge (Mars?). Personally, I think it would be Mars due to the availabilty of water etc. but I could also see an argument for Luna, especially if it had some rotation, so wasn't quite as extreme. Heck even the Asteroid Belt could end up being the Mainworld.

One thing that I hated about LBB5 was that you did all that work, rolled all those UWPs and ended up with 90% of the worlds being airless - like reality. WHY spend all that time?

Author:  hiro [ Wed Nov 29, 2017 3:31 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

Traveller's world gen forces retcon on an almost system basis. I've long since given up stressing over the fact that if you think about it for just one millisecond, you will question why the hell there are 200,000 people living on an airless rock when travel to a garden system within a few parsecs is so quick and cheap.

The retcon becomes the fun part of it. Making up some song and dance to be as believable as possible and fit with what the map has offered.

It does mean I don't take my Traveller games too seriously but I've retconned that to being a good thing too ;)

From a Traveller POV, for me, the important thing is what goes on on the planet that my character can interact with.

Statistically, there aren't going to be that many hospitable planets, how about the option of rerolling if a secondary planet turns out more hospitable than your already rolled main world?

Author:  thrash [ Wed Nov 29, 2017 5:08 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

hiro wrote:
Statistically, there aren't going to be that many hospitable planets...

Book 3 world generation results in something like 65% habitable main worlds -- any atmosphere 4-9.

Author:  hiro [ Wed Nov 29, 2017 6:00 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

I should have clarified.

What we know now suggests there won’t be many habitable planets, I wasn’t referring to Traveller.

I’ve not got the CE book in front of me but as I believe Sir Richard is writing with that in mind, what numbers does it propose?

Author:  thrash [ Wed Nov 29, 2017 6:39 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

It's the same as Classic Traveller: 2D6-7+planetary size, which in turn is 2D6-2. The Atmosphere Table (p. 169) includes pressure ranges, which is a later accretion, but is otherwise essentially the same as Book 3.

Author:  Cyborg IM1 [ Thu Nov 30, 2017 4:11 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

I intend to start with the CE version, which is identical for every version of Traveller, for Mainworld creation.

HOWEVER, I hope to offer a couple of Alternate Rules that could be used to create a more hard science feel to a setting, or just a region, if desired.

In the original LBB3, it clearly stated that the UWP system was to create "interesting mainworlds" for players to visit. This also assumes that the mainworld is in the Habitable Zone. LBB3 (and CE) do NOT use temperature, so if the ATM is 4-9, you almost have to assume it is in the habitable zone, since without life, you can't support free Oxygen in the atmosphere and life as we know it, requires liquid water on the surface, which means in the Habitable Zone.

I intend to add Optional Rules for non-mainworlds (which has never been done as far as I know) as well as expanding the UWP codes to include Super-Earths etc. Which would not be mainworlds, so there is no reason to have them in the original UWP world creation.

Since this is a GAME and not SCIENCE, I don't really feel I need to define the ATM much more than EXOTIC, CORROSIVE, INSIDIOUS - all based on what you have to wear to walk around on the surface. I intend to use the idea that a world with the exact same non-breathable atmosphere could be any of those three depending on Temperature, so I have to deal with that. Detailing the ATM (ala one of the supplements) isn't really necessary. In my Detailed World rules, you CAN do that, but won't need or want to very often, if ever. Does it matter if the ATM is Nitrogen or CO2 if the temperature is Temperate? You wear an oxygen mask and off you go; the ATM is EXOTIC. Same ATM at BOILING requires a Vacc Suit, so it CORROSIVE. Push it to 80 Atmosphere's of pressure (ala Venus) and it is INSIDIOUS) - again for 99.9% of the games, the details of the ATM are not relevent. If they are, I will have a table or ten that you can roll on to provide those details.

My struggle right now is balancing Science with Gaming. I CAN go down a lot of rabbit holes, but do I need to? Sometimes yes, sometimes no.

Author:  Cyborg IM1 [ Fri Jun 22, 2018 3:52 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

I am still working on this and have hit a bit of a cart/horse issue.

Do I need to know if a world is in the Inner, Habitable, or Outer Zone before rolling for it's size?

Since we really only have 1 entire planetary system as a reference, I need to ask help from the Planetary Science experts.

Again, I am intending to use the SMALL (SIZ 1-6) and LARGE (SIZ 7-C) classifications for terrestrial worlds. I have a system figured out for locating the Mainworld, Gas Giants, and Planetoid Belts. Now I am trying to fill in the rest of the orbits.

I hope to use a simple 1D6 roll to determine the size Class of the non-mainworlds - so really there are only two entries: Small and Large.

The question is: do I need 3 different columns or is a simple 50/50 rule (or something else) good enough?

I was thinking that the Inner Zone would tend towards smaller worlds, the Habitable/Middle zone would be 50/50 (or even more towards Large) and the Outer Zone would be back to smaller worlds tending to dominate. Nothing too radicaly, maybe 33/66 rather than 50/50 - so plenty of both sizes are possible. The Inner Zone would tend towards Small worlds due to the solar wind blowing a lot of the dust away during planetary accretion. The Outer Zone would tend toward Small since the density of material would be lower - but that is also where Gas Giants form, so maybe I should tend toward having larger worlds the farther away from the Star you go?

Need advice.


Author:  Cyborg IM1 [ Fri Jun 22, 2018 4:10 pm ]
Post subject:  Re: Traveller Heresy - World Classifications

BTW: I have finalized by Size classification system for worlds:

R - Rock - a term for an asteroid smaller than 1km in diameter (from Wikipedia)
S - Small - a term for an asteroid that is larger than 1km but too small to for hydrostatic equilibrium.
0 - Planetoid - Worlds from about 600km to 1600 km in diameter (hydrostatic equilibrium but not SIZ 1)
Small - SIZ 1-6 (1D6)
Large - SIZ 7-C (1D6+6) - this add two new world sizes to the UWP
SGG - Small Gas Giant (10-60 earth masses) (Uranus and Neptune)
MGG - Medium Gas Giant (50-300 earth masses) (Saturn and Jupiter - although Jupiter is right at the upper limit)
LGG - Large Gas Giant (500 - 3000 earth masses) - Upper limit is at the lower limit of a Brown Dwarf

The reality is that MGG and LGG are actually about the same size physically, but the term allows for a nice range to get you from Jupiter to a Brown Dwarf with regards to mass and energy output. The possible moon sizes also goes up with the mass of the GG, so having this extra category lets you have Earth-sized worlds orbiting a GG which is a SciFi staple without breaking our current theory of moon formation around gas giants. EDG had a nice write up on this a few years back.

I would love to get your feedback before I publish. :)

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