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.
GoalEscape
Early in the adventure, the heroes are captured. The remainder of the adventure consists of them learning enough so that they can escape. They have to get to know their fellow prisoners, learn the prison's routine, inventory their possessions, acquire other possessions they need, plan an escape, and execute it.
Story HookBetter Late than Never
Some bad guys have arrived and done some bad guy things. The PCs were none the wiser. The bad guys have now made good their escape, and the PCs have caught wind of it in time to chase them down before they make it back to their lair, their home nation, behind enemy lines, etc.
PlotA-B-C Quest
This is an epic sort of plot. In it, the heros are given (or undertake) a task to perform: The taking of a city, the rescue of an innocent, the destruction of a monster, the creation of a magical item, the defeat of a Master Villain, etc. But the path to victory is not a simple one. To get to their goal, Event A, they find that they must first accomplish some other task -- Event B. But when they undertake the task of accomplishing Event B, they find that they must first accomplish Event C. This goes on for several encounters, until the heroes accomplish all the obstacle events which prevent them from returning to Event A, their original goal.
ClimaxBloody Battle
This is the best Climax for an adventure involving the clash of mighty armies -- or for any adventure where, toward the end, the Master Villain and a large body of minions confront the heroes and their own troops. This finale is characterized by a monstrous clash between the two forces, with the heroes chewing through the enemy ranks to get at the Master Villain and his elite guards. It's strenuous, exciting, and classically simple.
General SettingUnder the Sea
This sort of high-fantasy adventure takes place in and under (not on top of) the sea. The heroes require access to some sort of magic item or spell that allows them to breathe water for long stretches, and might adventure in the uncharted depths or perhaps in a community of sea-breathers.
Specific Setting IMilitary Encampment
This is best used in an episode involving warfare; it could be the good-guy army's encampment, from which the heroes launch their adventures, or the villains' encampment, in which case the heroes might have to sneak in on a mission or escape from it if they're captured.
Specific Setting IIClassic Dungeon
This would be the standard monster-filled labyrinth; perhaps it's a nesting ground for the master villain's monster troops.
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 IInquisitor
This villain is the one who interrogates the heroes and NPCs captured by the villains. He accompanies the other Minor Villain out into the field and works on anyone captured; he enjoys inflicting pain and suffering.
Minor Villain IIChildhood Friend with a Dark Secret
This Minor Villain is like the character of the same name from the Allies and Neutrals section. However, the heroes find out early on that he's really working for the Master Villain. He may not wish to be helping the villains; his family may be held hostage, or he may just be too frightened of the villain or otherwise weak-willed to refuse. Alternatively, he could actually be evil now.
Ally/NeutralRomantic Loony
Somewhere, the heroes bump into a lunatic who falls immediately in love with a player-character and won't leave him or her alone. This character may be a love-smitten village lass or nebbishy adventurer. Whatever the origin, this character must be hopelessly in love with the character but have some trait which keeps the character from reciprocating; perhaps the loony is too plain, too crazed, or too stupid. Whatever, he or she really is sincere in his affection for the character.
Monster EncounterTerrain Monster
Don't forget the simple run-in with the animal belonging to the terrain where the heroes are: Every type of wilderness has its predators and big, nasty herbivores.
Character EncounterTruthful Accuser
This encounter is like the Lying Accuser except that the accuser is telling the truth. Dig through your characters' pasts, uncover a misdeed or two, and, when the heroes are at a critical point in their adventure, confront them with someone they actually have wronged. This person has found them and appealed to sympathetic local authorities. The heroes will have to make good or have the authorities on their backs for some time to come.
DeathtrapRock and a Hard Place
This trap starts out as an Animal Pit, Pit and the Pendulum, or Tomb Deathtrap, but an obvious escape suggests itself very early on. Trouble is, it leads into even worse danger. The hole out of the animal pit may lead to the lair of an even worse animal; it may lead through a succession of dangers (collapsing old catacombs, into an underground river, into a den of zombies) before the heroes reach the light.
ChaseHorseback
This is a relatively short chase -- it only needs to go on for a mile or so before even the best horses are winded. If it goes on longer than that, the horses may collapse and perhaps die.
Omen/ProphesyHero Fulfills Prophecy
This is the most useful sort of prophecy. In the early part of the adventure, one of the heroes discovers that he fulfills some ancient prophecy.
Secret WeaknessSecret Embarrassment
Finally, the villain may have some aberration or secret shame that will force him to flee when he is confronted with it. It could be something as simple as the fact that his nose is too big, or that he is a small and nebbishly wizard pretending to be some vast, powerful demonic power. When his shame is revealed, he is too humiliated to continue; this is a good option for comedy adventures.
Special ConditionCoping with a Curse
The curse might be making the hero progressively uglier, might be draining out his life-force (he's losing experience which will be retruned if he succeeds), or might be making him progressively insane. Each day, as he sees his reflection in a mirror or pond or fountain, he'll know himself to be less than he used to be.
Moral QuandrySaving Quandry
Finally, another classic quandry puts the heroes in the position of choosing between a grand opportunity to hurt the Master Villain -- or saving the lives of a number of individuals.
Red HerringFalse Path to the Artifact
Once again, if the heroes have had too easy a time finding the artifact capable of destroying the villain, give them trouble this way: When they get to the place where the artifact is supposed to be contained, they find the coffer or chamber or whatever empty, obviously looted by robbers, who have scrawled such remarks as "Kelrog was here!" upon the walls.
Cruel TrickWanted by the Law
One final complication, one which occurs pretty frequently, is when the heroes are wanted by the law. When they're wanted by the law, they have to travel in secret and very limited in the resources they can acquire.

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