DM's Adventure Writing Checklist

CHECKLIST
Genre and Themes: Stealth Heist, Raid, Dungeon Crawl, Hack-n-Slash, Intrigue, Mystery, Horror, Sci-Fi Fantasy. At sea, in secluded mountains, in a grand city, in a magic forest.
Premise - The goal and obstacles, or the Treasure and the Dungeon. Assassinate the Leader of the Merchant's Guild, Rescue the Princess from the Dragon's Lair, Steal the Tomb of Eldrich Horror from the Temple of Necromancy, Free the Thief Prince from the Evil Sheriff's Dungeon, Abduct the princess from her evil mother's castle in Alexandria and deliver her to her uncle in Lindblum.
Hook(s) and Incentive - The reason(s) why the players would care about the premise, and the Rewards for success. Have multiple hooks prepared and tailored to each player's interests and character's niche. Initial interested may be created by curiosity. A vision, dream, omen or prophecy, a scary fortune reading, a letter from a wizard.
Stakes - Consequences for failure or refusal. Something the PLAYERS care about should be at risk. What does the party stand to lose?
Inciting Incident - The event when things changed. The white knight was slain by the dark knight, the king fell ill and his brother became chancellor, the hunter killed the unicorn and became cursed for killing something so pure, the wizard disappeared the fellowship fell apart.
Conflict - Why do two sides oppose each other? Because if I get what I want, then you don't get what you want and vice versa. Biff can change the future with that Sports Almanac. We have to get it back, Marty!
Location - Town and Dungeon details. Mood, theme, genre, tone. Nearby features or locations, events, important people, shops and resources, factions. Sociology, politics, economics, religion, military, history.
NPCs - survivors, hostages, victims, witnesses, neutral entity, allies, patrons, contacts, mentors, factions or etc. - for Resources, Rewards, Tips, AND Directions!
Antagonist - Who are they? What do they care about and why? What do they do to try to succeed? What are their Strength and Weakness? The Sheriff of Nottingham excessively taxes the poor and is cruel to people who oppose him to keep everyone else in line.
McGuffin - A person or object for the hero and villain to compete for or fight over. Evil Tomb of Really Bad Spells, Royal Amulet, Ancient Ring of Power
Conditions or Complications - Specific Condition that adds a particular Interest, Requirement, Challenge, or Restriction. "You need a silver sword." "You have to be done by midnight." "Be discrete; The villain has eyes everywhere." "If the villain knows you're coming, he'll kill my dad." "The villain is actually your dad." "The evil dragon protects us from an even eviler dragon." "Get in and get out with the artifact, without getting caught, and don't wake the dragon." "The fortress is nigh-impregnable."
Setbacks or Sacrifices - an Opportunity or Resource that is lost adds tension and challenge. If you want to go through this door, you have to offer your blood. I will give you the key in exchange for your your magic amulet.
Surprise or Twist - Reverse Expectations; Use the audience's expectations against them. A betrayal? The plan failed because they knew we were coming all along. The strategy backfired because their weakness turned out to be lie? The wizard had a secret illness? The knight faked the thief's death? A seemingly good decision made for the right reasons turned out to be a grievous mistake?
Secret or Mystery and its Revelation - Villains secret weakness (bane) or Hero's secret weapon (boon). The villain's magic doesn't work if you know his true name. Only the sage in Mt. Doom knows, but what does he want for it?
Dilemma - Difficult choice between 2 things you don't want - "Pick your poison," or "choose your opponent,"or "choose the form of the destructor."
Moral Quandary - A particular type of dilemma where that party to do something that violates their ethos or alignment in order to achieve their goal or survive. "choose which one of your friends will die," Lifeboat dilemma where the lifeboat has room for 10, but there are 11 people. "Re: The prisoner dilemma. The lawful good paladin is obligated to accept surrender and to protect his prisoners to the death. The villain surrenders, but the NPC guide is prepared to kill the villain and anyone who stands in their way." Han Solo killing the Tonton to save Luke from freezing.
Red Herring - A clue, a tip, or false information with the effect of distracting or tricking the players. A false or incomplete answer to a riddle. X marks the spot, but there are two X's. A fake key.
Time Limit - Condition that creates a sense of urgency and tension. "If you don't figure out who the werewolf is and stop him before the next full moon..."
Climax - The location and circumstances of, who's present
Second Climax - "Just when the heroes think they're done..." or "You didn't think it would be that easy, did you?" or "Now, behold my true form." or "This place is collapsing! We have to get out, now!" A second smaller climax used to resolve a minor conflict can follow the climax of the major conflict so that the Falling Action part of the story falls more slowly and hopefully is more interesting; but sometimes a story that goes from 60 to 0 could be the best way to do it.
Resolution - What changes?
Suspense - Suspense holds interests. To create suspense, ask a dramatic question: "Will the heroes..." Always have one question open to keep your audience coming back. When you provide an answer, also provider another question. Make the players work for the answers and offer them as a reward. 

Tips
Alternate Between Good and Bad Encounters (Moments of Hope and Fear) - Things that are too good for too long become boring. Things that are too bad for too long get overwhelming. When you mix it up, you alternate between satisfying anticipation and providing something new for them to anticipate. Ask a dramatic question then answer a dramatic question, but provide an new dramatic question. Give the player an obstacle that rewards a tool, then give then a new obstacle that the tool doesn't work on so they have to get a different tool and the next obstacle suggests what kind of tool they might find.
Give the Audience What they Want: Writer's should deliver what they promise. People are only happy to have their expectations subverted when the thing they were expecting the whole time wasn't really what they wanted to begin with and so the subversion is actually a pleasant surprise. Reference the movie Shrek. The knight in shining armor is an actual ogre named Shrek and not some prince charming. The princess he rescues doesn't get married to Prince Farquad because she falls in love with the ogre, Shrek, but you'd expect her to choose the human over the ogre. If the movie waited until the end to reveal that Fiona was an ogre, it would be the same move but you'd have a very different experience because the ending you were expecting would have been intentionally set up like they were going to deliver it but they didn't actually plan on delivering it. By the way, foreshadowing is important or you'd be as in the dark as Shrek himself and you would probably pity his every effort get Fiona back at the end. There would probably be a sense of dramatic irony watching him enter the church in a hurry to object to the wedding which subverting would have been nice. Oh, and Chekhov's Gun is also important. You gave Princess Fiona a fight scene and showed off how athletic she was, but you didn't give her a bigger, more dramatic fight scene later?
Inter-Party Conflict: Pitting the players against each works for some groups but not all. One PC wants to resolve the quest one way, but another PC wants to resolve it another way, and they can't both get their way. "So, have you figured out which of your friends is the traitor yet?"
Verbs: Choosing good verbs is important. A good verb unambiguously tells the players what to do and how to do it. "Slay the dragon." The wrong verbs do not help your players understand their goal and how to accomplish it. "Investigate the mysterious plague." In the first example, the players know they need to find a dragon and kill it. In the second example, the players might not have a clear starting point or a clear plan. Investigation is not the ultimate goal, investigation is the means to identify the goal. the potentially resulting in frustration and wasted time. This can be solved by changing the wording. "Identify and stop the source of the mysterious plague."
The Players are the Stars: In general, players don't really care about the NPCs. Don't let any NPCs upstage them or be more important than them.

Combat Encounters - List of random and fixed
Roleplay Encounters - List of random and fixed
Exploration Encounters - List of random and fixed
Skill Checks - For each character's specialty so they all have a chance to shine
Traps - Mix of easy, medium, hard, and deadly
Puzzles - for the players to solve, not their characters
Treasures - Award at intervals, not all at once at the end
Secrets -
Create Opportunities for Creativity - Rule of Cool

 

What is a One-Shot Adventure?
    A one-shot adventure is an adventure that is intended to be completed in as little as one session. A one-shot therefore needs to be simple. The structure for a short one-shot adventure is:

1. Set up the conflict and establish the goal quickly.
2. Put the adventurers where the conflict is, where they will spend the length of the session.

Here's an example of a premise for a simple one-shot adventure:
1. The players arrive in a village and the inn keeper tells the players there's a monster and some treasure in some ruins in the forest.
2. The players go to the forest to search for the ruins. They enter the ruin to fight the monster and get the treasure.

In this example, the conflict is the ruins and the monster inside. The goal is the treasure. You can always start the players right at the entrance of the ruins and narrate that they just came from the village after hearing rumors of such and such in the village, they explored the forest, and finally discovered the ruins said to contain a monster and some treasure. The players will spend most of the session in the dungeon.

Too Simple?
Just because the one-shot is simple doesn't mean it has to lack excitement, motivation, drama, suspense or tension. To add these things, start first by introducing some stakes, then add complications, one or more twist, setbacks, and whatever else. The stakes are the consequences of failure besides failure itself. Players generally care about their reward more than the NPCs or the setting, so the reward has to be at stake.

Stakes: Let's say that someone was kidnapped and is being held prisoner by some bandits in the ruins mentioned above. The bandits are now ransoming this prisoner. The players are offered a reward by the family of the prisoner, but the bandits are threatening to kill the prisoner. No rescue, no reward. The players are now incentivized to care about the safety of the prisoner.

Tension: add a source of fear, stress, or restrictions. Let's add some more tension by adding a time-limit. Let's say the bandits have given the family an arbitrary timeline. The family has two days to pay the ransom or else they will kill the prisoner. Now, the players can't afford to take their time and may be likely to struggle between careful planning with swift action.

Complications: Ok, how can this get worse? Let's say that the bandit leader is not someone you want to fight. He's a very tough and cunning fighter, and he's known for slaying no less than five well armed and armored elite soldiers who came to capture him in a single fight. Maybe this is because he has a magic sword (this is a carrot and a stick).

Twist: What's something you're expecting to happen? OK, that doesn't happen (that's the best way I know to explain what is a twist). Once the players are half-way into the dungeon, they discover a twist. The prisoner, disinterested in living the life of a surf and craving excitement, asked to join the gang of bandits and has earned a place among them by defeating three of their fighters in one-on-one fights. Now there's no prisoner to rescue.

Setback: The players need to lose something of value, usually a resource like hit points but it could also be an important personal or quest item. This adds suspense. The more personal the setback, the more dramatically interesting it is. Rather than the ordinary challenges of the dungeon being the sole cause of their diminishing resources, one of the Named NPCs will cause it. Have one of the bandits, perhaps the Prisoner or some other bandit, sneak up on and backstab a player or picks one of their pockets. This bandit then escapes and calls for help from the rest of the gang.

Second Climax: What do you call it when the hero thinks he's won, then one more conflict arises right at the end, threatening to steal victory out from under him? OK, so once the players defeat the bandit leader and escape, the prisoner explains that he didn't join the bandits for real, he was just trying to create an opportunity to escape. He agrees to go home with the players. However, one of the bandits follows the party and wants to get revenge on the prisoner by killing him for betraying the bandits resulting in a hostage stand-off or another combat encounter while everyone's at their limit.
   To feel organic, and to not feel like the DM is just being adversarial, the bandit who shows up at the end should be someone the players previously encountered who they have some unresolved conflict with. This could be the bandit who called for help or sprung a trap or punched one of the players in the eye and ran away.

The end: The players get their reward of whatever amount of gp and a bunch of EXP. 

Tips for Mysteries
1. Plot: Know unambiguously the who, what, when, where, why, and how.
2. Make it clear that there is a mystery to solve. A type of mystery called a Closed Circle Mystery is a mystery that occurs in a small space with a set number of suspects.
3. Know the investigators. Why are they involved? What Magic or Technology do they have that can solve your mystery too soon or spoil your mystery? Create puzzles that work with these abilities, not against them. Don't completely restrict these abilities without a very good reason.
4. Clues. Give clues that lead investigators to the next clue. Give clear and simple clues. Prepare 3 clues for any direction you want to send the investigators in case 1 clue is missed or isn't enough. Give clues as rewards for ability checks and encounters. Avoid Red Herrings or false clues.
5. Avoid linear plots. A Diamond Plot structure offers the investigators choices for what order they want to investigate nest. Do this by planting one or more clues that lead the investigators in more than one direction from the start or very early.
6. Prepare for failure. What happens if the investigators find a dead end? Make floating clues that they can find anywhere that can send them to where they should be going. Be ready to improvise and be flexible with your plot.