Is this worth getting hold of?
I've already got Space 3ed, GT:First In & GT:Interstellar Wars.
Is there anything new in the 4th edition?
I'm specifically interested in star system generation.
I consider
GURPS Space for 4th edition to be one on the best RPG buys I have made. But you have to be very clear what you are getting. This is not a replacement for
GURPS Space for 3rd edition. The material formerly covered by 178 pages of
GURP Space 3rd edition is now split up among
GURPS Space,
GURPS Ultra-Tech, and
GURPS Biotech, at 240 pages each and the
GURPS Spaceships series that is coming out in 70-page pieces. The new
GURPS Space covers chapters 1, 2, 10, and 11 of the old
GURPS Space, in about twice as much detail, plus which it has a chapter on designing aliens and a chapter on space adventures.
I positively salivate at the thought of how much background descriptive detail about a Space setting you could get into a 240-page GURPS world book now. There would be no need for weapon and armour tables, spaceship construction rules, space combat rules, equipment lists, etc., things that take up about half of
GURPS Traveller You'd be able to take the first three chapters of
GURPS Traveller and triple the coverage and detail.
The planet generation sequence is monstrously clever. You can work it forwards or backwards: start with the planet's surface characteristics and work out where it belongs in orbit; or start with where the orbits are and work out what is in them. But it does have problems. For a start, it is very detailed and rigorous, which makes it tedious. I never did work all the way through designing an entire system in every detail including the day length of every moon of every gas giant (though arguably this is unimportant detail anyway). And the order of operations could be better if you were planning to apply every rule to every object.
Worse, there are problems with the rules for moons and their effects. The formulas for tide heights and tidal braking are wrong and SJG refuses to amend them. The system places large moons in way too close, resulting in severe tidal effects (tidal locking of most terrestrial planets with moons). The rules for day length are screwy. The formula for calculating habitability takes no account of day length, resulting in excessively high habitability ratings for planets with very long or infinite days.
The tables produce demonstrably too many systems with gas giants in very close or highly eccentric orbits. Too many class M stars. Excessive orbital eccentricity in planets that are neither the innermost nor the outermost in their system. And the rules for the development of an oxygen atmosphere on eligible worlds are rather pessimistic. The result is that you can generate a lot of systems without getting very many that have habitable world in them. This ought at least to be easier to adjust.
So. I still call the star system generation sequence very good. Four stars, say. With a page of errata and notes on adjusting it to produce more habitable systems it could be a five-star product.