
Haladir |

BTW, you don't actually need the Game Mastery Guide to run a game. The Core Rulebook is the equivalent of a combination of the 3.5 Players Handbook and Dungeon Masters Guide into a single rulebook.
The Pathfinder Game Mastery Guide is full of tips and tricks on how to run an effective game, like: the finer points on encounter design, setting mood and tone, plotting, world-building, and a rogue's gallery of pregenerated NPCs you can drop into a game. It's actually one of the best general-purpose guides on effective game mastering that I've encountered in my 30+ years of gaming. It also has a ton of random-generation tables (a throwback to the 1st edition AD&D Dungeon Master's Guide).
It does have some "crunch": rules for chases, ship-to-ship combat, sanity and madness, drugs and addiction, haunts, and adventure hazards, among other things. But these aren't central to the game.