DOWNLOAD: Explanator NSF


EXPLANATOR is a software for GDW’S SF-RPG Traveller. It uses a database of 15.000+ world’s, combines it with a search engine and generates 4-5 pages of text with information about the world.


Over 35 years ago, there was an article in Journal No. 10, called “A referee’s guide to planet building” by the fabulous, furry, Keith Brothers, which impressed me immensely. In those days, when having a computer, was nothing ordinary, I was the proud owner of a SHARP MZ-80K with dual floppy discs and a 7-dot matrix printer. An amazing 48K of memory was at my disposal, with 16K left after the BASIC language was loaded.

This article impressed me so much, that I started to write a program that should do what the article did.

Many, many years, many operating systems, and many versions later, I am still working on that software that does what the Keith Brothers did in that article. There is software available on the net that is very good in translating those dreary UPP numbers into long tables, but I never found something that “explained” a world. So I had to write it myself.

This software tells a story about the world you are on.

It starts with a description of your first impression of the planet once you open the airlock. Basically the software calculates an orbit around the sun that gives the world a temperature that will make it hospitable for humans. Then it generates the conditions the player will see and feel when they open the airlock (assumption is for hexrow 4). In this case the world is Craw, Spinward Marches, Glisten Subsector. The first paragraph is what you see and feel when you leave the ship. It is meant for the players, so they get an impression that they are not in Kansas anymore.

Craw C573645-5 Ni (Crawni) Asla8

1939 Spinward Marches


A small yellow Sun shines from a nearly cloudless sky. There is a gentle breeze. The mornings are cold, the nights are very cold, during the day it is chilly. The atmospheric pressure is comparable to earth conditions in an altitude of 1.1 km. The atmosphere contains highly contagious components. The air is quite dry. Gravity is about half of earth standard. A standard sized human (80kg) will weigh about 50 kg.

This is followed by a description of the sun and the solar system, the composition of the planet’s surface, as well as the physical data.



Craw’s sun is a Yellow Star (G7 V). It has a Mass of .894 and a Luminosity of .864. It’s perceived size is 55% SOL. The system has 11 worlds, 3 of which are gas giants and 2 asteroid belts. Craw circles its sun in Orbit 3.5, at a distance of 239.36 Million kilometers, one year has a duration of 708.85 planetary days of 26.47 hours, each. The planetary axis is tilted 33°. The majority of Craw’s surface is covered by land, with the exception of 3 major Oceans, 8 minor Oceans, 6 small Seas, 6 scattered Lakes.

Density : 1.00 Molten Core
Gravity : 0.63
Seismic Factor : 3.82
Air pressure : 0.93 Atm, 1199 m, Disease
Weather factor : 36% 0.0
Energy absorption : 86%
Native life : 6

This is followed by information about the government and settlements.


Craw has a population of 9.304 Million sentients. The world’s government is a representative Democracy. The world is governed by elected politicians. One to three powerful individuals control the functions of the government. The authority is undivided.

Craw has 80 large Cities with 100K+ Inhabitants, 115 Cities with 10K+ Inhabitants, 138 small Cities with thousands of Inhabitants, 156 Outposts with hundreds of Inhabitants.

Next comes an evaluation of the trade codes and the new T5 variables.

Craw is a non-industrial, very unimportant world, with average resources and a small labour force as well as a non-existent infrastructure. The overall efficiency is mediocre. The world generates 80 Resource units, which puts it in the 1% Range. The Homogeneity Rating is 45%, Acceptance reaches 29%, Strangeness is 30%, Symbols = 3.

Next part is the Starport. The software checks all worlds in a Jump-6 radius, if there is any traffic to that world, and how many daily tons of cargo and how many passengers will leave to that world. The traffic calculations are based on the GURPS Far Trader WTN/BTN formulae. It also tells you the exact amount and type of ships you are going to meet on your way from Starport to jump point and vice versa.


The port facilities are about average for its class. Craw has an orbital station, with a passenger and a freight terminal. The port has 40 landing pads, most of them equipped with a proper berth and one runway. Its traffic control can handle multiple takeoffs and landings at once. Unrefined fuel and all conventional ship’s stores are available, refined fuel is also offerd, but tankage is limited. All minor repairs and maintenance of ships up to 600t can be performed without undue delays. Handling of ordinary container cargo is efficient, though goods requiring very special handling will slow the routine. Modest but adequate shopping and restaurants, and usually some kind of entertainment, will be available for passengers and crews. Each year 18.098 passengers are handled and 308.633 tons of cargo shipped. The system has a low traffic volume.

The planetbound part of the port has an Anti-intrusion fence and a cleared buffer zone with patrolling guards, the patrols check it hourly. The whole port measures .5 by .5 km. The planetary Navy has a total tonnage of 4 kilotons, the flagship is a SDB of 600 t.



STARPORT CONTROL Zone. It covers the physical extent of the starport (on the surface or in orbit), a 15 km radius around it and up to 15 km above it.

AEROPSPACE Zone. It extends from the planets surface to 800 km above the surface.


Approach/Departure Control. Provides traffic control and separation that relies on craft adhering to published procedures within the planets AEROSPACE Zone. Also provides weather advisories and separation along flight path.

During the flight from the jump point to Craw you encounter 2 x Free Trader (200t), altogether 2 vessels.

To be cleared for landing, you need a bill of health for crew and passengers and you need to contact traffic control with your intentions as well as a customs declaration, also Landing and departure clearances, flight plan approval and a portside manifest or physical spot inspections.

The next part concerns the available trade goods, again in a descriptive format.

DAILY freight and passenger amounts:

MINOR ROUTE: New Rome (J-1) 273t, 4P. Aki (J-4) 174t, 12P. Glisten (J-3) 111t, 27P.

Available trade goods : Tiny amounts (-5) of Liquor, Grain, Canned food. Negligible amounts (-7) of Wood, Meat, Spices, Fruit.

Next to last follows an evaluation of the tech level, namely which technologies you can expect to find, as well as which weapons are allowed under the world’s law level.


SCIENCE 5 : The first synthesis of celestial and local laws of motion, usually along the lines of Newtonian mechanics. Engineering begins to rely on rigorous mathematics and empirical investigation of materials.

MATERIAL 5 : Large-scale production of hard steels, allowing their use as structural members.

ENERGY 5 : Steam engines, followed by the exploitation of wood and coal for fuel. Electrical energy appears late in the period, transmitted through local power grids and stored using simple chemical batteries.

COMPUTER / ROBOTICS 6 : Massive electrical calculating devices for specialized applications.

COMMUNICATIONS 5 : Longdistance communications via electric signals (telegraph and voice telephone).

TRANSPORTATION 6 : Fast railways and electric trains. Personal automobiles. WATER 6 : AIR 5 : Hot-air balloons and experimental propeller aircraft. SPACE 11 : Fusion rockets become practical, although the new reactionless drives are much faster and more efficient. Starships can be equipped with Jump-2 drives.

PERSONAL WEAPONS 6 : Auto rifles, Missiles, Light machine guns, Missile launchers are in personal use. Moderate Law. Allowed are Automatic weapons, Pistols, open carrying.

HEAVY WEAPONS 6 : Advanced indirect-fire techniques. Self-propelled guns (tanks). Large air-dropped explosives, including (late in the period) fission bombs.

BIOLOGY 5 : Theories of heredity and evolution put biology on a rigorous footing. Early cell biology. Germ theory of infectious disease.

MEDICINE 5 : Experimental vaccination techniques. Reliable anesthetics and antiseptics make radical surgery practical for the first time.

ENVIRONMENTAL 5 : Improved sanitation allows very large cities (PR 6).

The final part describes the temperature ranges in differing geographical altitudes, also known as hexrows.


When you start the Explanator.exe you can either enter enter the name of a world or start the search engine. There is no need to enter the full name or use capitalization. The software will show you all worlds that start with the characters you entered. After the list is finished, you have to enter the numbers for the world of your choice.

If you do not enter a name the software will start the search engine. You can define all the planetary characteristics with an upper and a lower limit. As result you will get a list of eligible worlds, this list will also be written to the directory. The file name is Worldlist.txt

Before the world is displayed you have the choice to enter values like temperature, axial tilt, length of day and gravity.  The file will be saved in RTF format, in the Explanator directory. After that the program will restart automatically.




  1. never mind… it was just printing the .txt file to the same root folder as the app. Sorry for the false alarm.


  2. The APP generates a file with the name of the world in the directory where it is installed, like this
    Alzenei A768895-C.rtf
    It should be readable with any word processing software.
    It’s important that all .DAT files are in the same directory as Explanator.exe

    Liked by 1 person

  3. This is very cool… I am on a Mac and have gotten through the World Selection steps… but I can’t find where it’s outputting the report. Where is the Explanator Directory? Is that something I access via Terminal (crossing fingers for a “no”)


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