A new campaign starts, and it’s time to form a cohesive adventuring party from a group of complete strangers. If coordinating with the players to create some sort of shared background is undesirable or impossible, it is up to the GM to put them in circumstances that demand cooperation. The trope of The Tavern and the Mysterious Stranger is standard fare by now; most experienced players have encountered this at least once, and most new players have at least heard of it. While meeting in a tavern is not necessarily bad, there are tons of other ways to throw a more or less random group of people together for an adventure.
Here are a few suggestions, some gleaned from various message boards, some are my own ideas. Several of these require GM fiat, but I tried to focus on scenarios which can be played by characters of any background. I’m sure you’ve seen (or played!) some of these before, so if you have any other ideas to help expand this list please feel free to do so. How you keep a group together after the first adventure is, of course, up to you, but many of these plots will provide the characters with either a common enemy or a common goal that you can build off.
1. Pirates! -- The characters are all passengers aboard an ocean liner when the ship is attacked by pirates. If they fail to repel the attack, they are captured and stowed in the holds of the pirate ship, locked in manacles. Do they try to escape and claim the ship as their own? Or do they wait to see where their captors are taking them?
2. Caravan Guards -- PCs are hired individually to serve as caravan guards for a trip (though some alternatively might be paying passengers). The caravan is attacked en route to its destination.
3. Prison Break -- PCs are captured individually and brought to a common dungeon. The reasons vary -- perhaps they were all found to be in violation of the city’s stringent weapons laws, or were practicing magic without belonging to a guild. Perhaps all of their names were scrawled on an incriminating note that was found on a dead body. Maybe their names are all the interrogators could get from the Evil Cultist that the authorities have locked in the dungeon. Or perhaps no reason is given at all *evil laugh*. Regardless, they must use each other’s strengths to escape
4. Parole -- PCs are captured individually or in pre-existing subgroups and are put in prison (see Prison Break for reasons), and either can’t escape or are not offered the chance. The King offers them all parole in exchange for services rendered.
5. Time Skip -- Players are all children growing up in the same village. Time skip 10 years forward and they are all meeting back up in the village.
6. Three Hour Tour -- Players are all passengers on a frigate that is shipwrecked. They must work together to survive until help arrives, or until they have devised some means of escape (the island shouldn’t be too far off shore)
7. The Chosen One(s) -- Players are approached by members of an influential faith, and their presence is “requested” at the temple. The players share certain qualities that mark them as potential “chosen ones” for an ancient prophecy, but the church cannot decide which one of them it may be. The players must undergo a group test/quest etc to determine which of them (if any) is the true Child of Prophecy.
8. Draftees -- A horde of hobgoblins is descending on the land, and the King has drafted every capable man (and woman) of the kingdom to meet the new threat. The PCs are placed together in a squad with an NPC commander who dies minutes after they enter the field.
9. Slave Uprising -- The players are all slaves in transit to their new master’s complex. One (or several) of them see an opportunity to escape, and they must work together to make good on it.
10. Royal Ball -- The PCs are all of noble blood and of marriageable age. They meet at the coronation ball of the new prince, where they are expected to greet other young nobles and make connections (either future business or marriage prospects). During the ball, armed radicals attack.
11. Waylaid by Weather -- The skies open and drench each PC as he/she travels the road to Harlandale for various reasons. They all take shelter in the same abandoned stone monastery at the side of the road (the only shelter around for several miles’ journey). The monastery may or may not be haunted.
12. Friendly Competition -- The players are all competitors in some sort of contest (perhaps a tournament put on by the King). Regardless of their performance, an NPC tops them in the standings, but the crowd suspects that he is cheating.
13. 28 Days Later -- The players are in the town of Faraway when a deadly plague hits, and they spend several miserable days (weeks?) in a delirious fever. When they come back to their senses, they find that they are the only survivors. They now all have a mutual immunity to the deadly plague.
14. Corporate Summit -- The PCs are all representatives of different guilds that are coming together to negotiate a contract. During the meeting they are attacked by a rogue guild (or anarchist party) who does not want the negotiations to be successful.
15. Field Work -- The PCs are all students at a university. They are called together by a mutual professor who wants to do some field work and needs some extra hands. Whether the professor survives the mission or not is up to the GM.
16. University Mishap -- After years of adventuring school, the PCs have all finally graduated. While attending a graduation party put on by a mutual acquaintance, the PCs play a drunken prank (described in hilarious detail by the GM) on another NPC student (the self-important, whiny, cowardly rich boy who has insulted each of the PCs at one point or another during their college careers). Unfortunately, the NPC is extremely well-connected. After a short trial, they are convicted and offered either prison or banishment.
17. Mining Operation -- After several months/years of hard labor in the mines of a repressive King, the sentences of the various PCs have been fulfilled and they are being released on the same day. With parting shots and/or whippings, of course.
18. The Odd Family -- PCs meet at an extended family reunion, and are perhaps members of various important branches within the family. When a mutual VIP relative is killed under suspicious circumstances at the party, the PCs are chosen by their respective houses to investigate and uphold the family honor.
19. Living Golems -- A powerful wizard had lived in comfort by enchanting many slaves, of which the PCs are several. When he dies unexpectedly, the PCs “wake” from their enchantment in the middle of the wizard’s tower, with almost no recollection of their arrival their or of their service to the wizard except nightmares which they all share. See Escape From the Tower for more.
20. Hazing Ritual -- The characters are all prospective members of a group (university, cult, explorer’s guild, etc). Part of the hazing ritual to determine who is worthy involves dropping all the prospectives (NPCs included) into a labyrinth/dungeon and seeing who makes it out alive. PCs get the opportunity to see several NPCs offed in various gruesome ways before meeting, to underline the idea that their best chance of survival lies with each other.
21. Mighty MacGuffin -- A legendary MacGuffin has been found by some field researchers, and it must be brought back to the King. Various powers (religious, royal, guild, etc) are interested in the success of this mission, and send the PCs along as representatives to make sure the job gets done. It would be a shame if an outside party managed to pilfer the MacGuffin before they arrived . . .
22. Dawn of the Dead -- Zombies are attacking the village and the temple (or tavern) is the only safe place to be. They must last out the night as the zombies close in around them.
23. Mini Mayhem -- An insane wizard is experimenting with the effects of extreme miniaturization, and the characters are his subjects. They wake to find themselves in an eerily empty town, where everything is constructed of strange materials. At some point, the wizard will reach down into the model town and pick one of them up for closer examination, and they realize that they have been shrunken down to about a hand-height. Escaping will require the ingenuity and cooperation of all.
24. Divine Interference -- A minor deity of mischief (or perhaps a lesser demon/imp) is bored, and has decided to toy with a group of more-or-less random mortals. The could be teleported to a common location (perhaps while some of them are engaged in. . . private business), or each handed a note (seemingly from someone that the PC knows and would trust) that tells them to meet at a specified place a few days hence.
25. Revolutionary Task Force -- The oppressive government of the Land of Faraway is opposed by the popular Revolutionary Front, to which the PCs all belong. Obeying some subtle signal (perhaps the wording on a poster advertising the upcoming gladiator matches), they all meet at a secret cell outside of the city. There, one of the leaders of the revolution forges a task force (which naturally includes the PCs, and perhaps one or two NPCs that can die mid-operation) to infiltrate an important government building and recover intelligence regarding troop movements.
26. Scouts for the Penal Colony -- The PCs are all founding members of a new penal colony, established on the outskirts of civilization. They are chosen by random lot to go on an extended scouting mission through the unknown, looking for likely farming areas, potential mining sites and unforeseen hazards.
27. A Series of Tubes -- The PCs are all visitors to Panera City during a coup by the Baron’s military tactician. In order to prevent tidings of his illegal usurpation of power to reach neighboring cities (and thus come to the attention of the King prematurely), the new Overlord is sweeping the city, arresting any foreigners they find and killing all those who resist. Each PC has been warned of the coming guard by sympathetic locals and has had time to flee into the sewers, where he/she will undoubtedly meet other political refugees.
28. Trine -- The characters have all been exposed to an ancient artifact that has the unwanted effect of binding their souls together. The players must find a way to undo the curse. In the meantime, the PCs cannot travel further than 100 ft from any other member of the group. Furthermore, a character’s death will weaken the collective soul significantly (if the party was 3 members, the power/health of the remaining two party members is reduced by 1/3). However, if the remaining party members survive the encounter, they can revive the fallen member with a lengthy ritual. All remaining members must participate for it to work.
29. Guilty Until Proven Innocent -- The PCs all happen to be in the marketplace when a man falls from the second story window of the tavern with a knife in his back. As the people closest to the scene of the crime, the PCs are dragged in front of the local magistrate as suspects of murder. They are probably not imprisoned, but may want to help with the investigation to help clear their names.
30. Misidentified Mishap -- The characters may or may not be seasoned bounty hunters, but none of them can resist the (ridiculously) large reward offered for the capture (not the death) of a famous outlaw. Trouble is, no one knows exactly what he looks like. While rumor-hunting in the local city, each PC is given a list of physical characteristics to look for -- characteristics that vaguely matches the description of a different PC! For example: “He’s a tall man in a red coat with blonde hair”. If the GM is really good, one or two of the traits should match several of the other PCs. If the intended party is mixed gender, make sure that the villain’s name is ambiguous (e.g. The Viper), and have some of the clues point to a man, and some to a woman. Set the PCs loose in the last known location of the outlaw (the one point on which all the rumors agree) and see if they can recognize their mistake before things get out of hand.
31. Voyager -- The party is comprised of prisoners of war, dangerous convicts and political prisoners, all sentenced to exile from Her Magesty's kingdom. Having recently come into possession of Telportia, a fortress of tremendous strategic importance, Her Grace has decreed that all exiles be sent through one of the unexplored portals. If the party returns successfully from wherever the portal leads, they will be given amnesty and rich rewards (enough to motivate those who have no other ties to the place). To aid them, they are given a "homing" compass of some sorts and a few provisions. Could start an epic travelling campaign -- a journey through exotic lands and legendary locales -- with the goal of returning home.
32. Set in Stone -- The characters are all victims of fate, turned to stone by a wayward spell in a crowded market place. They are reanimated several hundred years later, and find that the world they knew is gone. They must band together to survive in their new environment (political, natural, or otherwise). Alternatively, they could all be the victims of a common enemy, or perhaps they triggered a trap on their very first adventure (a feint on the GM's part).
33. Extraterrestrial Lab Rats -- Each PC has been abducted by aliens in the recent past, waking up to find him or herself irrevocably changed in some manner. Now news reports are coming in about others who have suffered the same fate. Will the character seek out the fellow victims, or will the government round them all up for an experiment of its own?
34. The Enemy of My Enemy -- The city has lately borne witness to a spree of vicious murders. While drunk with his own success, the serial killer has gotten a bit cocky and left a list of his intended future victims at the scene of the last crime. Each of the characters' names appear on that list, and the authorities bring them in for questioning (and possibly protection). If the GM can set it up so that a common contact or friend of the PCs has also recently been murdered, so much the better.
35. Lottery of Doom -- Each year the kingdom holds a lottery to choose victims for an unfortunate faith. This could be anything from being sacrificed to a rampaging dragon, venerated as idols in the national religion (to be sacrificed bloodily at the end of the year), to being selected for a series of deadly games to entertain the populace. Needless to say, the party members are this year's lucky winners!
36. Evil Has Trimphed -- The evil cultists have won! All of the party members have been sacrificed to the cults' Dark God, and have been reanimated as super-intelligent undead servants. While they still have limited free will, each PC will be compelled to do the cultists' will unless they find a way to break the effective geas.
37. Transporter Accident -- Through some technical glitch, all party members have been phased mostly out of existence. They can speak to and touch each other, but everything else is immaterial to them. They can walk through walls, etc, but can't eat/drink anything they weren't already carrying. No one else can see them and they are all presumed dead. If they can't find a way to become solid again, they will die of thirst within a few days. Could be done in a fantasy setting, just make it a wizard's experiment gone bezerk, zapping passersby out of the material plane.