Pulp Heroes started as a d20 mini-RPG found in Polyhedron Magazine issue #149 (also known as Dungeon Magazine issue #90). Polyhedron #161 (also known as Dungeon #102) contained a d20 Modern "update" of the Pulp Heroes mini-game.
The setting allows one to play games that take place during the famous Pulp Era of literature, filled with ancient dinosaurs, power-hungry gangsters, vengeful vigilantes, amazing superheroes, evil Nazis, bizarre inventions, mystical psionics, hard-boiled detectives, trained martial artists, curious explorers, eldritch aliens, and various other fantastic people, places, and things.
The worlds of H. P. Lovecraft's Cthulhu Mythos and Sir Arthur Conan Doyle's The Lost World, and famous individuals like Jules Verne, H. G. Wells, Doc Savage, Tarzan, and Indiana Jones serve as perfect examples of this era.
Many elements of Pulp Heroes were adapted into the later d20 Past sourcebook.