Core Rules Books:
.45 Adventure (Pulp Crime-fighting action).
Gloire (Swashbuckling).
Fantastic Worlds (Pulp Sci-Fi).
Broadsword Adventures (coming soon - Pulp Swords and Sorcery).
All these are stand-alone games that contain all you need to play. They use the same core system but each is a complete game on its own.
Amazing War Stories, The Gargoyle (Death Soldiers of the Jade Hood), Dragon Bones and Super Science Tales are rules and scenario supplements for .45 Adventure.
Under the Black Flag is a Piracy supplement for Gloire.
Thrilling Expeditions is, I'm led to believe, a dinosaur supplement for Gloire, Fantastic Worlds and .45 Adventure (it's quite new and I haven't read it yet).