Developing the Sandbox: The Campaign Calendar

This post is part of my series on developing the sandbox. You can read other posts in the series here. The series will, when necessary, go into detail on the development of my sandbox for Dungeon Module B1: In Search of the Unknown, but will also discuss sandbox development more generally. You can read play reports from my B1 campaign here.

A man of disputable wisdom once said that "YOU CAN NOT HAVE A MEANINGFUL CAMPAIGN IF STRICT TIME RECORDS ARE NOT KEPT." This has since become a bit of a meme in the TTRPG community. It is an emphatic declarative statement written in all caps by a larger than life figure in the hobby whom a lot of people enjoy ridiculing, often for good reason. But is there truth to it?

Kinda! Honestly, I've actually never kept a calendar for any of my D&D games. They still felt pretty meaningful to me. Nonetheless, at the end of my longest-running campaign ever (a three and a half year 5e game that took the player characters from 3rd to 20th level and beyond), I felt myself regretting not having a calendar. 

How long had it taken for the characters to make their ascent to power? How long had they known each other? When did they first meet that henchman? How many seasons, moon's turns, and holidays had passed them by? I didn't know.

I was running the campaign by the seat of my pants. I randomized the weather every day. It was an NPC's birthday or the day of some festival when I needed it to be. If a PC became a lycanthrope, only then would I bother to figure out when the next full moon was. Dungeons were restocked, new monsters moved into the region, and factions moved against one another and towards their goals when I felt like they should.

It worked for me. I didn't need a calendar, but I felt myself wanting one all the same.

One of the benefits of running a small sandbox (like the one I created for B1) is that you stand a reasonable chance of, at some point (possibly even before play begins), actually finishing prepping the whole thing for play. Technically this is possible for larger sandboxes as well, but it's a more Herculean task, and you are more likely to burn out before play even begins or to fall behind during play (if, like me, your interest waxes and wanes naturally as the campaign goes on), likely resulting in a lesser quality experience for you and your players.

The sandbox is never actually finished, because running the sandbox is its own thing that requires maintenance between sessions. The benefit of having most of your sandbox prepped and ready to go is that you have more time between sessions for those more ancillary pursuits. When you're not rushing to detail the owlbear den the players intend to clear out on their next expedition, you can instead spend that time restocking the dungeon, updating your outdoor encounter tables, and figuring out if those NPCs succeeded in their most recent scheme.

This is also a great time to work on your calendar. Now, the calendar might be one of those things you want to have prepared ahead of play. Perhaps you want to generate a month's worth of weather. That's pretty reasonable. But I've run nearly two dozen sessions of my B1 campaign, and I'm only just now feeling the need to create one of these bad boys.

What made me want a campaign calendar? Well, part of it was that I just thought it would be neat. That's reason enough. Part of it was remembering the regret I felt at the end of past campaigns. A big part of it was that the party started to accumulate an absurd number of NPC hirelings and paid them in advance, and the way that I was tracking the length of their employment was totally impractical. 

So, I made a calendar.

If you like, you can go on rootring and search "calendar", read all the advice, and come up with something that works for you. Like making a dungeon, there is tons of advice on this subject, and it's impossible to summarize without conducting a meta analysis.

Here's what I did. I got a calendar template from Google Sheets (I used the first option, which is just a sheet for each month of the year and a cell for each day of the month). This is a 2026 Earth calendar. There are no fancy names for the months of the year or the days of the week. You can do this if you want, but it isn't important to me, so I didn't do it for now (I remember really liking the vanilla fantasy names for the month presented by Shamus Young on his Twenty Sided blog...21 years ago?!).

First, I went back through my play reports and figured out when the campaign began. I had already decided that the campaign began in Spring, because that seemed like a reasonable time when adventurers would embark on adventuring activities. For simplicity, Spring is March, April, and May, Summer is June, July, and August, Fall is September, October, and November, and Winter is December, January, and February (this will be important when determining the weather).

I looked at when my first session took place in real life - March 12th. Perfect! I decided that was the in-game start of the campaign as well. Then, I went through my play reports, looking for any mention of the party resting or time passing. I also noted when the party brought on their hirelings and for how long. I ended up with this:

After 20 sessions and 6 months of play, just 13 days had passed in game. Wow! You could go more in depth, noting which sessions occurred during which days and what specific activities the party engaged in - and I might do that still - but it felt unnecessary at the moment.

Since one of the main reasons I wished to start work on the calendar was to track the length of NPCs' employment, I went into the future on the calendar and marked the days when each hirelings' employment would expire. At this rate, it will be another 5 or 6 sessions before the party's porters' and mercenaries' contracts need to be renewed, and 18 or 19 sessions before the crew of the party's river barge can retire, but it's useful information to know. Time passes weirdly during a campaign. A single day might be several sessions, and the next session might cover several days.

I also liked the idea of pre-rolling weather for a month or so. In the real world, you can often tell when it's likely to rain in the coming days, and I want to be able to foreshadow that (the players might not want to embark from town if it seems like they're going to get a torrential rainstorm the next day). It also allows me to skip rolling for weather at the table, and makes me less likely to forget to do so. So, I rolled weather for the rest of the month (as well as the following month, since we're nearing the end of the current one).

I used these hex flowers to determine the weather:

I like these because they're evocative, they only require a single roll for each day, they're based on the seasons, and each day's weather affects the next day's weather. Depending on your system of choice and how weather mechanically impacts things like overland travel or encounter chances, you'll likely have to do some interpretation of the results, but it works reasonably well. In addition to marking daily weather on my calendar, I noted if the weather imposed penalties on overland movement or modified outdoor encounter chances for that day.

Since I am using a real-world calendar, I could also look up what the weather was actually like on each day in some area of the real world comparable to my setting, but in practice I found the information I was looking for too difficult to find, and the information I did find too fiddly for my uses. It would be fun to use a system where the weather can change throughout the day, as it does in real life, but I personally don't need that.

Another thing I thought would be fun and necessary to track is the phases of the moon. This information can be based on the real world and is pretty easy to find, but you can also just make it up. Pick a day during your first month that the moon is full, then have it be full again every 29 days or whatever. Or decide that full moons in your setting are more or less common if you like. You'll have to come up with that yourself. You can also track other celestial events like eclipses and supermoons the same way.

Why is the moon important? Well, don't tell my players, but my sandbox has lycanthropes in it. I want to know when there's increased lycanthrope activity. The player characters might in turn become lycanthropes, and I want to know when they're going to transform and wreak havoc, or do whatever it is werebears do (for example). The AD&D DMG has this whole table breaking down the percentage chance of a cursed individual transforming into a werebeast based on the current phase of the moon:

Clearly you will need to accurately track the phases of the moon to use this thing properly! Also note that you will need to know for how long the character has been a lycanthrope. Another win for the campaign calendar!

You might also decide that the local Evil temple does some nefarious stuff during the lunar eclipse or that magic is more powerful during that time. That seems like a fun application of this tech.

Another fun thing you can do with your calendar is track settlement events like holidays, festivals, NPC birthdays, or whatever. If the players plan for their characters to spend a week in town, it would be nice if they knew that it was the friendly wizard NPC's birthday so that they can arrange to get her a gift. If they're planning to venture out into the wilderness but they learn that tomorrow is the annual Cheesemonger Parade, they might decide to stick around an extra day to attend the festivities and rub elbows with important contacts in the cheese industry.

I roll a d20 for each day on my calendar, and a result of 18+ is some day of significance in the settlement. I like this table from the 2014 5e DMG:

This is one of the many unsung tables of that oft-maligned book, which is honestly full of useful little stuff like this. You'll have to ignore some stuff - seasonal events like equinoxes and solstices, midsummer/winter festivals, fertility/harvest festivals, and celestial events which you're already tracking by other means - but overall this is pretty good stuff!

I wouldn't bother determining events like this for every settlement in the sandbox. I simply rolled for the largest settlement - the one the PCs are most likely to spend extended amounts of time in. You can probably safely assume that the villages, hamlets, and thorps which surround your town celebrate more or less the same events as the town itself.

There's also no reason to limit this to settlements only. Do the denizens of the dungeon celebrate holidays? Is there some mutually recognized armistice day where they come together and parade through the dungeon? Do monsters in their lairs celebrate birthdays? Is a tournament being held at the fighter's stronghold?

You might also want larger events going on in the background - wars and famines and natural disasters and stuff. Joel at Silverarm Press wrote a post which highlights a neat table from uh...Oriental Adventures, on which you can roll for a single yearly event which in turn influences which monthly events are likely to occur. This is pretty neat tech. I haven't tried it out yet, but it's worth a look if you want like, a war happening somewhere "off screen" (or maybe even on it). Warren D. of I Cast Light! also reworked the table on his blog.

Just as you might do with weather or the phases of the moon, you can also pull yearly/monthly events from real life. Simply pick a real-world year that corresponds roughly to the period during which your campaign takes place, Google it, and look at the Wikipedia article to see what happened that year.

The calendar is also useful for tracking faction events. I know that the wizard that rules my town has a tenuous truce with the cleric who rules her own stronghold. The wizard also has a mutually friendly working relationship with a subordinate wizard who wishes to build a stronghold of her own. The cleric wants to kill the subordinate wizard. Will the cleric achieve her goals? Will the truce deteriorate? When does that happen? You will probably want some way of running factions.

You might also use the calendar as a simple timer. One of my biggest bugbears in adventure design is when some time-limited event is happening in the setting (a monster is growing in power, a city is being overrun with plague, or a bad guy is working on a nasty ritual), and the conditions of those ongoing events don't change unless the player characters intervene somehow. 

There's something to be said of a "powder keg" scenario where everything exists in a tenuous equilibrium, requiring some "X factor" (the player characters) to move things decisively in one direction or another, but that doesn't mean everything has to remain static. If some event is going to occur if given enough time to gestate, you should track it somehow. No more Big Bad Evil Guys waiting until the player characters show up to complete their rituals!

There's a party of adventurers camped out in the wilderness, clearing land to build their stronghold. When do they finish? The wizard in town is plotting against them, trying to recruit a band of ogres to root them out. When does he get the ogres to act? There are brigands who have usurped a stronghold and keep its rightful ruler prisoner. When do they execute her? Set dates for all of these things on your calendar. If the player characters take actions to aid or thwart these plots, adjust the timeline on your calendar.

These are the broad strokes. The campaign calendar is of near infinite utility, and there are many things both big and small which it can be used to keep track of. Here are some examples of what else you might track:

• When does a disease or parasitic infestation run its course or kill the afflicted?
• When do followers arrive at a player character's newly built stronghold?
• When does an NPC spy complete a mission and, if the mission fails, when can the characters safely employ another spy on the same mission?
• When does a slow poison kill?
• When does a character or NPC finish crafting an item (magical or otherwise)?
• When does a sage find the answer to a question (or discover that the question is unanswerable) and when can another question be asked of the sage? When does the sage finish acquiring a new minor or major field of study?
• When do henchmen respond to recruitment attempts?
• When does an unfaithful cleric finish atoning for their sins?
• When must an Evil cleric reassert control over their undead minions?
• When does an injured player character make a full recovery?
• When do effects like psionically induced comas, magical enchantments, or temporary insanities end?
• When does a character who mixed an oil of slipperiness with an oil of etherealness return from being lost in the Ethereal Plane? 
• When is a soul no longer trapped in an amulet of life protection, when does a character finish reading a manual of bodily health, and when can a character again invoke the Goat of Terror, and other magical item effects?
• When does an assassin finish their study of poisons?
• When does a character finish their training and level up?
• When is construction of a font or basin for holy water completed?
• When is spell research completed?
• When does an Evil artifact inflict its malevolent effects upon its possessor?
• When has a character known a hireling or henchman long enough to warrant a loyalty score increase?
• When does a character finish training a griffon as a mount and when do they finish training to fire a bow from its back?
• When does the next peasant rebellion occur? When does the rebellion evolve into a civil war?
• When do the characters have to pay taxes?
• When does a cleric or magic-user finish creating a golem?
• When is a paladin's warhorse or a conjured demon released from service?
• When is construction of a stronghold (and mazelike dungeons thereunder) completed?
• When does a character die of old age?

(This list was created by combing through the AD&D DMG with Ctrl+F, keywords "days", "weeks", "months", and "years". There are undoubtedly a great number of many other things you can track as well!)

The calendar is not just for the DM's benefit. Just as players can master a dungeon's layout and use their knowledge of such to plan optimal routes for exploration, treasure extraction, and avoidance or ambushing monsters, they can master the calendar and use it to their benefit. If the DM knows when it will rain, when the hirelings' contracts expire, and when the NPC's birthday is, this should be telegraphed to the players in some way so that they can make informed choices.

Do they wait another day in town to let the weather pass? Do they prioritize their next expedition, before their hirelings demand more money? Do they make sure to be back in town so they can attend the wizard's birthday? There's a full moon tomorrow night. Should they plan to patrol the streets of town and lay a trap for the werewolf? When are the owlbears out hunting versus sleeping in their lair? What can they do before the royal ball to improve their chances of getting an invite?

These are all more or less things you will have to track as a result of player actions - they are less about developing the sandbox than they are about running it. You can wait until your game is underway and until you absolutely need the calendar before creating it (as, admittedly, I did), but hopefully I have demonstrated why creating the calendar upfront can be beneficial as well.