Sooooo, what to do in the world of “Ghosts of Mars”? After all, an RPG is not only about the world but what the PC are going to do in this world. As the “main event” going on is “the Ghosts of Mars are on the loose and about to eradicate every human they encounter” the following scenario arcs come to my mind:
A) The road to salvation
What do you do if you are on a planet where there is an unstoppable threat that’s sole purpose is to hunt you and every other men down? Leaving this planet comes to mind. The characters would be a rag-tag group of colonists that survived (or escaped) one assault of the “Ghosts” and now try to reach a settlement (or major logistic hub) that at least has a shuttle port.
The aim: locate a shuttle, secure it and get it to work and leave Mars (in hope of getting picked up by a ship in orbit… or to just stay in orbit as long as possible in hope of ship to arrive).
The game: the GM will need to prepare a starting point A and a map with one or more “end point X” (where the characters have a chance of securing a shuttle). Furthermore, the map needs different locations the PC either need to pass in order to reach one of the X or that the characters will want to explore in hope of getting resources. It is good to have the characters starting out with a vehicle similar to a half-truck… just because it helps them to carry supplies and motivates them to loot locations for fuel (or fuel cells). Same is true for water, food, medicine weapons and ammo. With the “prep work” done, the game will become a hexcrawl with the characters roaming freely, finding situation x and searching for resource z to overcome it. Add some random encounters based and some planed encounters and you are close to “ready to go”. “Close to” because a game without human interaction between PC and NPC is robbing the RPG of its “R”, unless your read this as “roll playing games” instead of “role”… or if your players are damn good at inter-PC-roleplay!
Thereby, have other survivors (NPC) added to the characters. They can provide drama, guards, help, valuable skills and a host of problems… and if they do none of it, they still provide roleplay opportunities. Last but not least, it is good to have a source for replacement PC if one of the players PC dies prematurely.
B) Let´s go to ground
When somebody is not able to fight a threat and does not want (or: does not see an option) to run from it, the only thing left to do is hiding. Hiding can be done in two ways: the characters can “secure” a location, turn it into a defensible position and hope to survive long enough to see the cavalry coming or one adopts a nomadic lifestyle, looting resources and evading dangers as much as possible.
The aim: the GM needs to provide a wider area as above, but this time he should set a number of days that the character need to survive till “the cavalry” form Earth arrives. It is about fighting through something, but exploring and evading. The characters will be about avoiding contacts, scouting sites before entering and avoiding fights as much as possible… because a fight draws attention and might mean that one needs to leave the wider area again. Rotating between three to five “large areas” might be name of the game.
The game: The characters are advised to pick a vehicle, the GM is advised prepare a larger “hunting ground” and it still is a hexcrawl. In addition, the GM might need to provide another, larger area while he runs the “first one”, because once everything is looted the characters will want to move to greener pastures.. unless of course there is a reason why they have to “stick” to their sandbox (like, the limited range of their vehicle and an inability to get the train). In that case, certain locations will be visited more than once, and that is a good thing: the characters will never “clear” a dungeon as they leave disembodied “ghosts” behind.
In both cases the game is a hexcrawl and the GM should keep it open if the characters really have a chance of making it. The whole thing could be doomed to fail right from the start, but the GM should never play such a thing if there is at least one player that dislikes “pre-programmed failure”. Asking all the players ahead of the game IF they would be fine with an “unhappy ending” is fine… and even if they would like it, it is fair to have a happy end for those who survive. If the players know that it all MIGHT have been for naught from the start, the GM will have his audience on the edge of their seats when he narrates the final. If the players are fine with it, tell them you will roll for it at home, on a 50% basis, even if you don´t 😉