A superb set of tools for GMs running any sand box campaign (works particularly well for SciFi, but many of them would work well for Fantasy or whatever) - the ideas boil off the page.

Plus there are a full set of RPG rules - and what looks like a very good system to make spaceship battles fun at the table (though I have not tried them).

A brilliant resource for any GM - has a set of the most excellent tools for sandbox world building. Plus full set of OSR rules, an intersting setting and more..