Session Zero: The Cheapest Worldbuilding You'll Ever Do

Part of the $25 Campaign Challenge

Here's a dirty little secret about Session Zero: it isn't really for the players.

Oh, they'll think it is. They'll arrive with snacks, character concepts, and a warm feeling that you care deeply about their creative vision. And you do! But you also have a campaign world with the population density of an empty parking lot, and these people are about to fill it for you. For free.

Today we're talking about running a Session Zero that sets expectations, locks in your house rules, and quietly outsources a chunk of your campaign building to the people sitting across the table.

What should you prepare before Session Zero?

Before Session Zero, send a short campaign pitch and ask each player for two or three character ideas. Give everyone enough flavour to understand the world, and make it clear they'll help shape it. The point is flexibility: characters should fit the campaign without anyone feeling stuck with a concept that doesn't belong.

A little prep smooths things out enormously.

Send a short pitch. Three to five sentences. Not a novella, not a lore bible, not a slide deck (I say this as someone who has a PPT addiction). Just enough flavour that players get a sense of the world, plus a clear heads-up that they'll be helping shape it.

Ask for two or three character ideas. Not one. And definitely not the one they've spent two hours lovingly backstorying since the eighth grade. The "character I've wanted to play my whole life" is a wonderful thing right up until it doesn't fit the campaign and someone spends session one quietly annoyed with you.

Flexibility is the ask. We want to accommodate everyone, but nobody should walk in feeling stuck and nobody should walk out feeling bereft. That's a rough way to start a year-long relationship.

Which house rules should you explain at Session Zero?

Explain the rules that will change how characters play, progress, or get along at the table. For my campaign, that means critical hits and fumbles, playing for the shared story, Luck instead of Inspiration, buying proficiencies, and training time. Players deserve to hear the restrictions before their characters run into them.

Session Zero is the perfect time to lay out your house rules. Here are mine. Borrow them, bin them, I won't be offended. (I'll be a little offended.)

Critical hits and fumbles. I use a table that came with Fantasy Grounds, because the results are either dramatic or, better, hilarious. Nothing bonds a party like watching the fighter fling his sword into the rafters.
Play for the table. I ask players to make character choices that improve the story and the shared experience for everybody. "It's what my character would do" is not a legal defence.
Luck instead of Inspiration. This comes from Kobold Press's Tales of the Valiant (Black Flag) rules. It is tremendously better. You're welcome.
Buy a proficiency. Characters can pick up a new proficiency by "buying" it with 10% of their experience points. It's a real commitment, so it doesn't happen often, but the option is there for the barbarian who really, really wants to learn the lute.
Training time. To reach the next level, you train one week per level. Moving to 7th? Seven weeks. This slow rolls the campaign and gives the world room to develop, time to pass, and the villains a chance to react to the characters’ actions. (I'll waive it if they stumble across something like a powerful celestial creature. I'm strict, not a monster.)

Whatever restrictions you build in, address them here. Mine have never caused a problem, but players deserve to know where the guardrails are before they hit one at full speed.

How do player backstories build your campaign world?

Player backstories give the campaign people, places, history, and unfinished business. Ask for those stories at Session Zero, then keep the details you can use later. A family history supplies lore; a rival supplies an enemy; a missing relative supplies an adventure. Multiply that by everyone sitting at the table.

The Main Event: Tom Sawyer and the Fence

Now for the fun part: tricking your players into doing your worldbuilding.

Remember Tom Sawyer convincing his friends that whitewashing a fence was such a rare privilege they'd pay him for the chance to do his chores? (Too obscure? Stay with me.) That's the move.

We tell players we want their backstories. They think it's for them. It is! It's also for us.

If someone wants to write three pages about their family history going back 200 years, more power to them. That's 200 years of lore I didn't have to write.

For the players who are just here to hit things with sticks (a completely valid lifestyle), we build a backstory together at the table. I use a free backstory generator here (It's technically a Pathfinder site and it adds some details I skip, but it produces a half decent character in about 15 minutes of rolling dice.) There are paid options, an excellent one in Xanathar’s. The free one works fine. (This is the $2 DM, what did you expect?)

What should you listen for in a character backstory?

Listen for relationships, significant past events, and crossover hooks that could involve the whole party. Write down family, mentors, enemies, debts, and unanswered questions without editing as you go. The useful detail is often the one you can bring back later, making a player's history matter to everyone at the table.

Whether the backstory arrives as a three-page epic or a string of dice rolls, keep a notepad handy and jot down:

Relationships: family, mentors, enemies, that one guy they owe money to
Significant past events you can bring back later
Crossover hooks: threads that could pull in the whole party

Don't edit as you go. Don't stop to wonder whether an idea is stupid. Just get it all down. You'll sort the gems from the gravel later.

Crossover hooks are the real gold. If a player mentions their aunt went mysteriously missing two weeks ago, congratulations: you now own that aunt. The aunt, the aunt's family, or (dark, but effective) the aunt's body can turn up in a future adventure, and your players will absolutely eat it up. It rewards the work they put into that backstory, and it makes the world feel real. It doesn't even matter whose aunt it was. Suddenly everyone at the table lives somewhere with consequences.

Can a human fighter's backstory create a whole city?

A simple human fighter can supply a city's poor district, prison, church, criminal underworld, and a guard with a grudge. Those locations and relationships come straight from the character's history. Add connections to the other players, and one backstory becomes a pile of shared contacts, enemies, and adventure hooks.

Worked Example: The Plain Oatmeal of D&D

To prove this works, let's roll up a human fighter, widely considered the most boring character in the game. Here's what the generator handed us:

Raised in a city. Only their mother is still alive.
One full sibling and two half siblings, one older and one younger. Which raises an obvious question: what exactly was the arrangement between Mom and Dad?
Born lower class, among peasants and slum dwellers. (The generator also offered begging as a childhood career. We passed.)
Mother was a thief. Father was a peasant from the countryside.
Imprisoned at a young age. Which, given Mom's line of work, tracks.
Never saw themselves as a criminal. Wanted to be a great warrior, inspired by legends of the past.
Grew especially close to a holy person in the community who fundamentally changed their life.
Caused a civic or military official to suffer through inaction, disregard, or recklessness. And felt pleasure about it.
Has never had a romantic connection of any kind. Maybe painfully shy, maybe aggressively off-putting. Either works.

Look at that. Our oatmeal is now a 1950s street drama. The young punk from the wrong side of town gets taken in by the local minister (who, by the way, is the one who taught this kid those legends) and grows up to be a great fighter. Yo, Adrian.

Somewhere in the background is a town guard who unjustly branded our kid a criminal, then later lost his job or got hurt, and our fighter felt a little glow of satisfaction. How do they feel about that now, after finding religion? That question alone is worth a session.

Now look at what happened to the campaign world. We've got a big city with a poor district, a prison, a church, a criminal underworld, and a guard with a grudge. Contacts, enemies, and adventure hooks, all from a lookup table. Sure, these are stereotypes, but you need stereotypes before you can play against them.

Then we tie the fighter to the rest of the party with three quick randomized connections:

Player one: same hometown, same corner of the city.
Player two: rivals who grew up competing with each other.
Player three: known only by reputation. From the criminal back streets? From prison? From the church? Your call.

Fifteen minutes of dice rolls and you've got a pile of rich, meaty hooks. Now multiply that by every player at your table.

How do you launch the campaign after Session Zero?

Bring the characters together somewhere they have a reason to be, then give them a shared event to react to. My campaign starts in a tiny island village, using the opening of Storm King's Thunder as a parts bin. A massive battle and a couple of quick encounters get the campaign moving.

I've done my share of ranting about the big published adventures, and Storm King's Thunder has taken its lumps from me. But its opening chapter, A Great Upheaval, is a free download on the DM's Guild, and it's an excellent way to launch characters into a campaign.

We're not running Storm King's Thunder. We're running our own campaign and borrowing its best opening.

At the end of Session Zero, the characters all meet in a tiny island village and figure out why they're there (born there, raised there, moved there, running from something there). Then they witness a massive battle and have to deal with the aftermath. Toss in a couple of quick encounters so everyone gets a taste of what's coming, and we're into the campaign proper.

Free opening. Free backstory tool. Player-built world. Sensing a theme yet?

Frequently Asked Questions

Session Zero can do more than settle house rules. It can give you a shared world, connect the party, and turn character history into adventures. These are the practical questions behind this approach: what players should bring, how much backstory they need, and how to make that material useful at the table.

What should players bring to Session Zero?

Ask for two or three character ideas and a willingness to help shape the campaign. Send a short pitch first so they know the flavour of the world. Flexible ideas are easier to fit together than one character somebody has already spent hours perfecting.

Does every player need to write a long backstory?

No. Welcome the three-page family epic from the player who enjoys writing it, and build a backstory together for the player who would rather hit things with sticks. A free background generator can supply relationships and past events to discuss at the table.

How do you turn a backstory into an adventure hook?

Write down relationships, significant past events, and unanswered questions. Then look for something that could involve the whole party. A missing aunt can return through her family, her disappearance, or its consequences; a rival can connect two characters before the first adventure starts.

Do these house rules replace the published game rules?

These are the house rules I use for my own table. Borrow them or leave them. The point of Session Zero is to explain the choices and restrictions your campaign will use before anyone runs into them during play.

What does this Session Zero cost?

This Session Zero costs $0 in the $25 Campaign Challenge. The campaign has spent $5 so far, and player backstories add worldbuilding without another purchase. The free backstory tool and opening adventure do the jobs needed here; the paid alternatives mentioned above are options, not part of this session's spending.

Goal: one full year of campaign play for $25
Spent so far: $5
Spent on Session Zero: $0

That's right. Not only is it Session Zero, it's Cost Zero.

Next up: More in-depth note taking

Next time, we're digging into more in-depth note taking, because a year's worth of hooks is useless if you can't find them. Like, subscribe, and stay tuned. You'll pay for the whole seat, but you'll only need the edge.

Roll high, spend low.

— The Two Dollar DM