Random Adventure Generator

ThemeAction/Adventure
This is the most common and straightforward sort of adventure there is. In the Action/Adventure scenario, you present your characters with a task and then confront them with obstacles to overcome in order to accomplish the task successfully.
GoalWin War
In this adventure or set of adventures, the characters become part of an army -- a force assaulting another kingdom, perhaps, or an army defending one realm from another.
Story HookOld Enemy
This is a straightforward story hook; the hero learns that his oldest enemy is back and is very active in the campaign, up to something. The hero will naturally want to investigate and will walk right into the story.
PlotEvent
For this plot, choose some sort of event -- a tournament, a holiday, a celebration called by the king, a masked ball, or whatever -- and set the commencement of the Master Villain's plan against that backdrop.
ClimaxScattered Duels
In this climax, the heroes have gotten to the end of their quest -- they may have broken into, sneaked into, or escaped from imprisonment within the villain's citadel, or have marched into the little town where the villain is holed up -- and they become separated. You can separate them by having traps and tricks break the party apart, by having them see two or three things they must resolve (such as danger to innocents or the appearance of minion villains) pop up simultaneously; they'll have to run in all directions at the same time or suffer failure. Once the party is broken down into bite-sized chunks, you confront each individual or small group with the enemy or enemies he most deserves to face -- his personal enemy, the monster which defeated him before, etc. -- for a grand series of climactic duels.
General SettingTorturous Terrain
The adventure takes place in some sort of unsettled, uncivilized, dangerous terrain; in action stories, the desert and jungle work best; choose one of those two or decide on a setting that is similarly dangerous and exotic.
Specific Setting ICatacombs
These can be catacombs beneath a living city or a ruined one; they can be long-forgotten or still in use.
Specific Setting IIDemi-human Community
In wilderness areas, this will be a large community of demi-humans -- elves, dwarves, halflings, whatever -- or intelligent nonhumans such as orcs. If your action is taking place in a city, this could be a hidden community (such as a secret underground dwarf community) or a section of the city inhabited mostly by demi-humans.
Master VillainConqueror
This character is moving his army in to take over; that's what he lives for. He's been the enemy of your characters' nation's ruler, and has launched a full-scale invasion of your characters' favorite nation. The heroes have to beat their way through or elude his hordes of soldiers in order to get at him; better yet, they might lead their own nation's troops against his and outthink him in military fashion.
Minor Villain ILovable Rogue
This character is like the Master Villain of the same name, except that he has no minions of his own and serves at someone else's bidding. However, he's very independent, not always working in his employer's best interests; he often makes fun of the Master Villain's pretensions and may suffer that villain's retaliation because of it.
Minor Villain IIHard-Eyed Advisor
This is the sort of villain whom the heroes see in the Master Villain's throne room. He's hard-eyed and scary; life means nothing to him and he enjoys killing. He's also a good advisor to his master.
Ally/NeutralGrumpy Old Professional
Again, the heroes need an expert in a certain field -- this time a craft or art, such as blacksmithing, engineering, horse-training, or whatever. The only or best professional they can find is an aged expert. He's grumpy, cranky, and sharp-tongued; he constantly complains about the food, the weather, his companions, the decline in skill of his co-workers since he was a young man, the road conditions, the rotten pay he's receiving, and so on.
Monster EncounterPowerful Tester
Here, some powerful, intelligent monster with shapechanging ability turns into a human form. When the heroes encounter him, he is in need of help or having trouble. He also obviously can't reward the heroes for their help, and will only serve to slow the heroes down from their quest. If the heroes help him anyway, the Powerful Tester reveals himself in his true form and offers to aid the heroes in their quest.
Character EncounterBandit Gang
When the heroes are en route from one place to another, have them run across one of the local bandit gangs. The bandits are faster and far more numerous than the heroes. But the bandits stay back. Basically, they're bandits who admire courage and prowess, and the bandit leader will challenge one or all of the heroes to a test of bravery or ability -- such as a horserace, a duel, a wrestling match, a joust, an arm-wrestling match where scorpions sting the loser, etc.
DeathtrapTomb Deathtraps
Another classic type of trap is the sort of triggered trap left behind in abandoned tombs, ruins, and catacombs. Here, a hero who touches the wrong step, floor tile, wall brick, torch bracket, mounted gemstone, or other device will trigger some sort of ancient trap designed to kill tomb-robbers and intruders.
ChaseFootrace
The chase involves the characters on foot, probably through such terrain as city streets or the corridors of a palace. One hero may realize that the's being pursued by a party of enemies and choose to run for it; the heroes may have caught up to the Master Villain, prompting him to run for his life.
Omen/ProphesyComet's Progress
Events during the adventure may be enlivened by a large and menacing comet which appears in the night sky for several days during the scenario; the locals take it for an omen of doom. The comet may be the result of magic being used by the Master Villain, or the comet's appearance can pertain to an old legend involving the Master Villain.
Secret WeaknessElement
The Master Villain can be banished, dispelled, killed, or otherwise defeated by some of element or item. The Master Villain tries to get rid of all the examples of this element in his vicinity; he doesn't let his minions carry it or bring it into his presence. But he's not stupid; he doesn't announce to the world what his weakness is. He tries to hide his concern within another command. If he's allergic to red roses, for instance, he orders all "things of beauty" destroyed within miles of his abode.
Special ConditionOmnipresent Observer
If a wizard, demigod or god has forced the heroes to undertake this quest, he may be with them continually -- in spirit. He can't help them, but does magically watch everything they do. And when they do something he doesn't like, he tells them about it -- loudly and nastily. (This is distressing when they're trying to break into a fortress or sneak through enemy lines.)
Moral QuandryHonor Quandry
You want to use this on the character with the most strongly developed sense of personal honor -- someone who has lived all his life by a strict code. Toward the end of the adventure, this character realizes that the best way to defeat the Master Villain is a violation of that code. For instance, the character might be a paladin, who discovers that the only possible way for the heroes to defeat the Master Villain is to sneak up on him and stab him in the back.
Red HerringExtraneous Details
When giving the heroes details on their enemy -- for instance, details they are learning from investigations and readings -- you can give them just a few details too many. This may prompt the heroes to investigate the "extra" (i.e., irrelevant) details in addition to the relevant onces, thus losing them valuable time.
Cruel TrickVillain Accompanies Party
In this distressing situation, the Master Villain, in disguise or his secret identity, accompanies the heroes for much of their quest. He gets to know them, learns their strengths and weaknesses, learns their plans, and just as soon as it's most efficient for him, he thwarts their current plans and leaves. Alternatively, the Master Villain might be with the heroes all along, up to the very end; the heroes know that one of their companions is the villain, and the whole thrust of the story is finding out who he is. This is the whole purpose of most Mystery-type adventures.

Based upon tables from the Dungeon Master's Design Kit by TSR, Inc.