There are two other modes of play for a pulp game that seem very workable to me, and they are related, or at least distant cousins.
For anyone who grew up thrilling to the adventures of Indiana Jones (or, depending on your vintage, to the adventures of Scrooge McDuck and his daring nephews on DuckTales), the pulp adventure par excellence is a globetrotting adventure to exotic locations in search of lost treasures.
To even think of Indiana Jones is to remember a red line creeping its way over a map, leaping from dot to dot until it settled at some remote port of call.
This is certainly the style of the classic Call of Cthulhu adventure MASKS OF NYARLATHOTEP, which is much more pulp adventure than cosmic horror. In that cultist-punching classic, heroes start in Manhattan and follow a trail of clues around the world to London, Africa, Southeast Asia, and even Australia. The HORROR ON THE ORIENT EXPRESS adventure, as well as the CURSE OF CTHULHU mega-adventure, also fall into this style.
That this mode of campaign is evocative of the modern classics of the genre suggests that it's probably the best mode for a pulp campaign, and it's my favourite of the "top three". A game that jumps from location to location means you're always going to have new opportunities for breakneck chases, mysterious temples and hidden tombs, and sinister bad guys who want the same gold-plated geegaw that Our Heroes want -- except they think it would be niftier to use it to Rule the World, ha ha ha ha ha!!!
A traveling campaign also presents an opportunity to spin character drama in a non-linear way, as player characters encounter personal "baggage" from past adventures (in the form of swarthy bad guys or lost loves, or possibly angry exes skilled at drinking Nepalese strongmen under the table). Any number of triggers for flashback scenes or bold declarations about a character's colourful past could be presented as the characters race from place to place. This could turn the traditional problems with such a campaign -- the lack of a stable "hub" for the game with familiar sets and supporting characters -- into a dynamic advantage.
The third mode is a more focused version of the second -- the expedition. In this style of game, rather than visiting many locations over the course of ten-twelve episodes, the players would plan and execute an expedition to a single exotic location they would explore in some detail. This is the mode of HOLLOW EARTH EXPEDITION, although there are so many "niche" adventures in that setting (dinosaurs! Atlanteans! mole men!) that it might as well be a globetrotting game. Another classic Call of Cthulhu adventure, BEYOND THE MOUNTAINS OF MADNESS, may be the perfect example of the form.
This would be more like a campaign-scaled version of the Cairo segment of RAIDERS OF THE LOST ARK. You could possibly run two or three episodes of set-up and background, then run the bulk of the campaign at whatever exotic location the player characters are searching for lost treasure / civilizations / their Nazi occultist counterparts. A nearby city or port of call might form the base for several expeditions into the wilderness on the trail of glory, providing that stable "hub" I talked about before, with lots of swarthy NPCs and seedy dives for fistfights.
Focus works to increase realism, I think, because you've got more opportunities to layer in particular details that make your setting vivid. (As I said in an earlier post, however, realism isn't as much a concern for me in this game.)
Next Episode! Will Dauntless Donovan escape from the whirling sawblade trap of the mad Aztec warlord Professor Mictlan? And what other pulpy goodness can we jam into a campaign? How big should we go? STAY TUNED!