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.
GoalExplore a New Area
The heroes are hired or convinced to enter an unmapped area and explore it. They may be making a map; they may be trying to find someone who disappeared into this area in the past; they may be following legends that tell of treasure in the unexplored interior.
Story HookOld Friend
Another classic story hook is the Old Friend, the childhood friend of our hero, who shows up in one of several ways to drag the hero into the story.
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.
ClimaxDivine Retribution
Here, the heroes' goal has been to alert the gods that the Master Villain threatens them or their plans; in the last scenes of the adventure, as our heroes face an overwhelming enemy force, the gods bring down their divine retribution on the villain, causing a massive earthquake, tidal wave, lightning storm, or flood of monsters. This is all well and good, but the heroes are too close and must escape the fringe effects of this awesome disaster. A variant on this is the Natural Disaster. No gods are actually involved, but the Master Villain has been tampering with the delicate forces of nature. He may, for instance, have been powering his master spell with the energies of a volcano. When the heroes attack the scene of his spellcasting, the spell goes out of control and so does the volcano. The villain is consumed in the eruption and the heroes must escape or be consumed themselves.
General SettingUnder the Ground
In this variety of adventure, the heroes descend into vast cavern networks beneath the earth's crust. There, they can encounter bizarre races and primitive tribes, hitherto-unknown monsters and strange landscapes.
Specific Setting ITavern/Inn
This is a classic fantasy setting, the residence of travelling heroes and the home of the tavern brawl.
Specific Setting IITemple/Church
This can be either the church of some lofty and good diety, or the dark and grisly temple of some horrid deity (doubtless filled with evil soldiers and monsters), or even the temple that the madman villain has dedicated to himself for when he becomes a god.
Master VillainRavager
This Master Villain is like the Destroyer, except that he terrorizes a very limited area -- such as a village, island, castle, or clan stronghold. (He may want to destroy the whole world but be trapped where he is; perhaps his efforts to free himself constitute the adventure's plot.) He stays in his area and terrorizes whatever comes into it.
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 IISingle-Minded Soldier
This most trustworthy of villain minions is the experienced, competent, persistent soldier -- a field-trained officer who serves the villain with military precision. He is usually encountered in the field as leader of the villain's field operations. He is not encountered directly until the middle of or the latter part of the adventure; until then, the heroes encounter only his subordinates.
Ally/NeutralObsequious Merchant
This fellow is the owner of the caravan the heroes are protecting, or the merchant the heroes encounter when they desperately need to buy something. He is oily, ever-flattering, overly agreeable, and is a sharp bargainer; the heroes will not find him willing to give them a sale price.
Monster EncounterBeast Amok
Some time when the heroes are in a village or city, an animal, probably an otherwise tame or captured beast, is set loose by the villain's minions or driven mad by the Master Villain. The beast goes berserk in the crowds; if the heroes aren't inclined to capture or kill it, it goes after them.
Character EncounterThief
At some point in their adventure, the heroes have a run-in with thieves.
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.
ChaseWater
Don't forget the water chase: Whether it's a battle of seamanship between naval vessels, a chase of rafts toward the inevitable waterfall ahead, a contest of canoeing ability, or a chase between the villain and his giant shark vs. the heroes and their dolphin friends, the water chase can be a distinctive and dramatic one.
Omen/ProphesyBirthmark
One of the heroes has a birthmark that pertains to the adventure in some way. He may have a birthmark identical to some NPC -- for instance, some person endangered by the Master Villain. This mystery can give the hero his reason to become involved. Alternatively, his birthmark may mark him as a hero fulfilling 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 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 HerringArtifact that Doesn't Work
Often, epic quests against powerful Master Villains require that the heroes find some legendary artifact, the only object which can defeat the villain. If your heroes have had no trouble getting to the artifact -- they've effortlessly sliced through every obstacle you've put in their path and are confidently advancing on the resting place of the magical item -- you can have it not work.
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.