How To Run a Casual D&D One Shot

A friend of mine is sizing up a D&D one shot session for some family this holiday season to parry the dreaded holiday tabletop routine. I think this can be great fun if everyone's into trying to play a tabletop RPG together. Your enjoyment may vary of course, but I wanted to share the advice I gave her here in case it proves useful to you. While D&D isn't the ideal tabletop RPG for every group of people or occasion, it is currently the most recognizable name in the genre. Getting people past their curious stage is often easier when they feel at least a little familiar.

Picking The Module

You're always free to homebrew your one-shot, but often you want to be able to show up and play about as easily as you would another board game like Risk or Monopoly. Reading the 300 page PHB is likely not what a curious casual player is ready to commit to just yet. They want to know what this whole D&D thing is about with only a little commitment.

Likewise, spending a few days crafting the perfect one shot only to have your group grow board forty-five minutes in is going to hurt about as bad as being the first one bankrupt in Monopoly. To simplify your work, I'd suggest picking a one page dungeon. There are a great deal of them available for free or a few bucks. You can find everything from lovingly handcrafted award winning modules to randomly generated freeware maps. Whatever you're most interested to run has almost certainly been built by someone else before you. Possibly with a bit of player testing behind it to polish the design. Some places to look online include:

When picking, try to find an adventure that feels like it'll fill about a half to a third of the time you intend to play. The more players you have the slower the party progresses. Ideally aim for three to four players not including the DM. Don't expect to play for more than about four hours because after that the DM will start to feel exhausted. You'll probably complete about one encounter per hour. Encounter here could mean combat, puzzle, or social interaction. This speed declines with each additional player. This time also includes the time to get between each of the encounters, roleplay around the encounter, setup, and resolution so a bunch of encounters all back to back will go faster but be careful not to overload it. Aim for what feels like not enough because too often one-shots don't finish in time.

Designing The Session

While 1st level characters are great for a long campaign, they can be tricky to run as a casual one shot for new players because 1st level characters are very squishy. Picking something like 3rd or 5th level means your players can feel fairly powerful, you aren't as likely to kill them with some savage rolls, but they're not so powerful they have dozens of abilities they need to learn and keep track of.

The very first thing to pick will be the CR of your session. This first because it helps balance the level of the PCs to monsters they'll encounter. Of course this is only if your module doesn't already have this figured out. CR isn't a formula, but more a rough guide to help you create new fights. It helps you feel confident your CR 7 boss monster with a couple CR 3 minions is probably manageable but tough for a party of four 5th level PCs. Just remember that CR doesn't predict if the encounter is fun, memorable, or manageable. If it were, we wouldn't need a DM. You can calculate a CR table using donjon's 5e Encounter Size Calculator.

If your players are brand new, first encounter(s) will probably have your players taking actions that are extremely novel until they get the hang of what's optimal in the action economy. I've had players throw their coat to try and blind monsters, attempt to blast down chunks of the ceiling on them, cast Mage Hand to shove them, and spend a turn checking out what's in a nearby crate. Really try and go with these. The DM's job is to create drama (tension and resolution) but also to facilitate fun. You can always scale things by fudging health and damage, or just use plot to salvage a really bad situation. It's fine for the monsters to try and take someone hostage for ransom, have a distraction owlbear attack giving the party a chance to escape, or any other deus ex machina to cover for a badly balanced encounter or some seriously unlucky dice.

Creating Characters

When it comes to character creation for a casual one shot with novice players, the character creation process may be a bit much. Creating characters is a lot of fun for many, but for a new player expecting only a couple hours of fun, it may be overwhelming to spend 2 hours before the game to create their first character. I'd suggest you come with a party of ready character sheets. You could also write a small backstory for each to help your players get a sense of who this person is and what their class can do. For example:

Hantus Faringray, Human Bard

After spending the last 12 years as librarian in the service of king Daemian, I was abruptly deposed from office. I find myself in near exile, unable to procure work. I have therefore taken refuge within a band of mercenaries. Though of lesser pedigree, I nevertheless vowed to aid them in their quest to explore the ancient ruins. In exchange for my inspiring insights into the habits of local monsters, advanced fighting techniques, and arcane magics of antiquity they have agreed to provide me part of the spoils. I fancy myself a jack of all trades, knowledgeable about much of the world. A book may not substitute for wisdom, however, I am confident in my abilities to inspire my new companions in the heat of battle. Besides, I do love a good party. Not to worry though, my knowledge of Vicious Mockery is always there to aid me in case things get hairy. I did not spend that 6 month sabbatical at the college of wizards for nothing now.

This isn't the same as having them build their own character, but definitely saves hours of playing the, how to build a character, D&D pre-game. One way to help them feel more agency though is don't give the characters all their skills/spells. Let your players spend a bit of time looking through the PHB to personalize their character. A wizard having to pick twenty spells is going to take a while so maybe give them spell schools that have a pack of spells and reduces the choice to three or four options. You can also make up a reason that spell casters can only know their prepared spells like the wizard having lost their book or the warlock's patron being on an interdimensional vacation. Also, remember you don't have to make all this up yourself. There's a number of places to find premade characters online:

Running The Session

When running encounters I highly recommend Evan Bailey's Improved Initiative. It's an amazing shareware tool that manages to make running encounters extremely simple and efficient. If you're using monsters not in the SRD you'll have to manually add them yourself but once you have you can export them for later import (or login and automatically cloud sync if you pay to support the project).

The only other tips I've got:

Encounter Severity
Save DC10 to 1112 to 1516 to 20
Attack Bonus+3 to +5+6 to +8+9 to +12
1st-4th Lvl Dmg1d102d104d10
5th-10th Lvl Dmg2d104d1010d10
11th-16th Lvl Dmg4d1010d1018d10
17th-20th Lvl Dmg10d1018d1024d10

For a short adventure, the focus is definitely going to be monster killing and treasure collecting. The social and roleplay will come when they encounter a puzzle or decision they have to make in your dungeon. The best bet is to start with the players already in front of your dungeon. Maybe even start mid battle. A hot open can really set the right pace and tone. It also means you don't have to use one of your encounters to start in a tavern, get them to obtain the quest, and then get them to the dungeon. You can just give that in a blurb up front.

Dealing with the town's werewolf raiders has fallen to your party. If you don't successfully stop their return tonight by the full moon the town is surely doomed. Having infiltrated their lair and taken care of the sentries you made your way to their outer den. Unfortunately a wandering patrol has spotted you and raised the alarm. You're surrounded. Roll for initiative!

Further Reading

That's about it for a casual one shot with novices. I mean, most of this is just my opinion so there's a lot of blog posts on the topic:

Ultimately it's going to be a lot of contradicting advice because D&D is about getting a sweet spot. Enough structure but not too much, enough drama but not too much, enough combat but not too much, etc. Just try to have fun with it and remember that your players are most of the fun. Hopefully a cooperative game can make the holidays just a bit more bearable, even if only among your cousins.