This was unexpected. If you are looking for a feasible solar system creation, with appropriate wording and classification, then this is really cool. It uses scientific numerical notation and classification, which may server well for hard-scifi or realistic The Expanse like fiction. Concepts are mostly explained, although not their notation or the meaning of the possible values that you can get from the tables, i.e. you can get the volatile state of orbital bodies with their exact composition and numerically valued temperature zone based on the sensor observation.

I give this 4 stars because value is very high, but the formatting is very chaotic, sometimes you see tables with proper table forms, and other times you see just tabulated text in between two paragraphs. Recommended if you are looking to create detailed scientific-backed bodies in a galaxy.

This is a bold attempt to provide a lot of detail when generating any part of a game-universe, at least as far as we currently understand the "real" universe (or think we do). There's a lot of detail here - arguably too much for many potential universe-designers - but it's fairly easy to pick and choose those parts you may actually want for your own game. Personally, that'd be primarily parts of the planetary system tables, which have far more detail than I'd thought of for my own home-brewed system generator of 25+ years ago, such as major chemical-element relative abundances - but then we (think we) know more about planetary systems now than back then anyway!

There is the question of how long parts of this will remain current, given the huge increase in the numbers and types of "real" non-Solar System planets discovered by various techniques just in the last 5-10 years. That could mean tweaking the relative likelihood of encountering certain planetary forms in different parts of a star system, for instance. While that probably won't matter much to most gamers, it may impact on the book's claimed usefulness as a teaching-aid for youngsters, astronomy enthusiasts and any factual writers who may use it.

The main downside is the text assumes quite a high level of pre-existing physics-astronomy knowledge. There's no glossary of terms, some of which aren't explained at all, such as "billion" (presumably the short-scale "thousand-million" version, also called the "milliard", rather than the long-scale "million-million", because that's the short-scale's "trillion"; "trillion" also features here undefined, million-million-million on the long-scale), "parsec" (roughly 3.26 light-years, 31 million-million kilometres or 19 million-million miles) or "AU" (= astronomical unit, the mean distance between the Sun and the Earth, almost 150 million kilometres or 93 million miles). Other terms, like "Me" ("Mass of the Earth") are used, and then only later explained. In a work of this type, size and overall considerable complexity, this is disappointing, and could mean some of its potential users will be put off doing much with it. Maybe there's an argument here, as with many RPG systems, for saying less (complexity) would be really more (useful).