Early on in my discussion of the Planetary Romance genre, I mentioned a quote from Wikipedia regarding the common conventions of the first book of a Sword and Planet series, which I'll repeat here for the sake of easy reference.
"Burroughs established a set of conventions that were followed fairly closely by most other entries in the Sword and Planet genre. The typical first book in a sword and planet series uses some or all of the following plot points:
A tough but chivalrous male protagonist, from Earth of a period not too distant from our own, finds himself transported to a distant world. The transportation may be via astral projection, teleportation, time travel, or any similar form of scientific magic, but should not imply that travel between worlds is either easy or common. The Earthman thus finds himself the sole representative of his own race on an alien planet. This planet is at a pre-modern, even barbaric stage of civilization, but may here and there have remarkable technologies that hint at a more advanced past. There is no obligation for the physical properties or biology of the alien planet to follow any scientific understanding of the potential conditions of habitable worlds; in general, the conditions will be earth-like, but with variations such as a different-colored sun or different numbers of moons. A lower gravity may be invoked to explain such things as large flying animals or people, or the superhuman strength of the hero, but will otherwise be ignored. (A Princess of Mars, however, when it was first written did loosely follow the most optimistic theories about Mars - e.g., those of Percival Lowell who imagined a dying, dried-up Mars watered by a network of artificial canals.)
Not long after discovering his predicament, the Earthman finds himself caught in a struggle between two or more factions, nations, or species. He sides, of course, with the nation with the prettiest woman, who will sometimes turn out to be a princess. Before he can set about seriously courting her, however, she is kidnapped by a fiendish villain or villains. The Earthman, taking up his sword (the local weapon of choice, which he has a talent with), sets out on a quest to recover the woman and wallop the kidnappers. On the way, he crosses wild and inhospitable terrain, confronts savage animals and monsters, discovers lost civilizations ruled by cruel tyrants or wicked priests, and will repeatedly engage in swashbuckling sword-fights, be imprisoned, daringly escape and rescue other prisoners, and kill any men or beasts who stand in his way. At the end of the story he will defeat the villain and free the captive princess, only to find another crisis emerging that will require all his wit and muscle, but will not be resolved until the next thrilling novel in the adventures of...!."
As I had mentioned in that earlier post, this gives us a nice blueprint to use for the first few adventures in a Planetary Romance setting. Using something like the screenwriter's Nine Act Plot Structure as the basis for a campaign story arc, it occurs to me that you could easily use something like the following to help launch a strong Sword & Planet campaign.
Over the course of the campaign, we reveal the background of the campaign arc through small scenes and insights. As this is not a formal scene within the screenwriter's plot structure, neither is this an actual adventure for the players.
The characters arrive via some mysterious means on a distant world, which will be the setting for the entire campaign. Just as they begin to familiarize themselves with their new environment, they find themselves caught in the middle of a struggle between two different factions, and must choose sides. Obviously, as a beautiful woman needs saving, they will side with the faction that rescues her.
The party must prove themselves to their would-be compatriots, and protect the woman from the barbaric ways of the natives. This starts off with some political/social machinations, possibly with duels or combat to help establish the players in a new social position. As the party relaxes and begins to enjoy their newfound position, a jealous or vengeful second in command, displaced by the party due to their arrival and success, kidnaps the woman and flees with her into the night.
Following the kidnapper, the party comes upon the enemy of the woman's people. These enemies happen to desire the woman as well, given that she is a Princess and the daughter of their enemy. Their first encounter with the enemy warlord defines his arrogant manner, and displays his position of power within the world, a position that the players will not be able to overcome at first, simply because they didn't grow up on this world. The enemy warlord and the kidnapper will leave the site of that first encounter, and the players will be left alive to lick their wounds and plan the next step in their quest to rescue the Princess.
Following the enemy warlord, the party travels across wild and inhospitable terrain, confronting animals and monsters, before arriving at the capital city of the enemy's empire. Upon entering the city, they immediately hear that the enemy warlord will be marrying the Princess, and be elevated to the Right Hand of the enemy emperor as the governor of the Princess's homeland, to rule in the emperor's name. The party must stop the wedding.
Having decided to stop the wedding and save the Princess, the party must identify the ways by which they can enter into the palace, execute their plan and rescue the woman. Every complication encountered as they proceed toward their goal is harder and harder, challenging them to be creative and action-oriented whenever possible. They barely succeed in fighting to save the Princess, only to have to flee into the subterranean dungeons beneath the enemy city. The Princess then demands to be taken back to her native city to warn her father of the impending attack on her homeland.
In travelling through the underground ruins in search of an exit, the party risks being captured by cultists that have captured prisoners, including children, to sacrifice to the monster they worship as a god. One of the prisoners will offer to show them the way out, if they will free the prisoners and help them to escape as well. Upon leaving the dungeons, they will come upon the enemy warlord's flagship in the upcoming invasion, a small flying warship that they can use to escape.
The party makes for the Princess's homeland, the enemy close at their heels. There may be an encounter or two with advanced scouts, enough to slow down the party long enough for the enemy warlord to catch up. The prisoner that originally helped the party escape the dungeon offers to sacrifice himself by crashing the flagship into their enemy, leaving the party to cover the short remaining distance to the Princess's homeland and warn her people. As the party watches, though, the flagship is taken out by the enemy warlord's more powerful vessel, giving time for the party to barely make it to the city and raise the alarm.
The party escorts the Princess to her father, only to find that the kidnapper is in the Great Hall and is about to poison the greatest warriors of the land with bad wine. The party takes care of the kidnapper, explains the situation, and fights the good fight. The final fight scene should involve the party and a handful of warriors against the invading enemy warlord and his soldiers, in a final climactic battle atop the greatest towers of the city, where all can see the results of this battle. If the Princess can be in the clutches of the enemy warlord and be rescued as a result of the fight, so much the better.
There is much rejoicing. If a party member is interested and has played up the romance well all the way through, this is the point where he might become betrothed to the Princess, otherwise that honor goes to an NPC. Either way, there's a large celebration taking place at this point as honors and awards are laid upon the heroes for their part in all of this. Just as the wedding ceremony starts, the party is whisked away by some mysterious force, either to return to Earth or perhaps to be sent elsewhere on the world by powers beyond their ken...
It needs a lot of work, of course, but this should make for the start of a great campaign. I'll likely spend more time polishing the story arc up, adding some more elements here and there, and removing some of the railroady factor from parts of it as I continue to work on this concept. Of course, any thoughts or suggestions you might like to share would be greatly appreciated.