I'm prepping a hexcrawl-style game, my first sandbox game ever, and I'm expending all the online resources I can to learn how to run them and prep them. I'm actually having a lot of fun (and work) doing it; I've completed the map, placed key locations, also created landmarks for dungeons and adventure hubs. I have 3 settlements (being a post apocalyptic fantasy I don't plan to add more), 1 secret village, 13 dungeons, 12 monster lairs, 10 ruins. The world is highly hostile and most encounters will be combat based.

So, as I've been investigating, people often uses "don't prep too much" as tip, however this beign my first time on a sandbox campaign I don't know how much prepping is "too much".

My fear is that my players run into something I haven't prepared yet, since I'm terrible improvising adventures. I can easily improvise wilderness encounters, however I don't know what I'd do if my players run into a dungeon I haven't mapped yet so I'm mapping pretty much "everything" beforehand, which makes me wonder if I'm doing it "right".

My players aren't the "cooperative" type when it comes to world creation (tho I love my group), so, any tips to know when to stop and what to do to avoid "prepping too much" on games like this?

  • 1
    \$\begingroup\$ This has been covered by this general prep question rpg.stackexchange.com/questions/5870/… and this one specifically for sandbox: rpg.stackexchange.com/questions/21700/… \$\endgroup\$
    – mxyzplk
    Jul 19 '14 at 3:00
  • \$\begingroup\$ Hey I'm going to close this for the moment - I think it's a duplicate, unless you think you have a unique part to the question (it's tagged 5e but I see no difference in tips from any D&D-ish sandbox). I can merge the answers from here over to the dupe once we're settled on what's happening. \$\endgroup\$
    – mxyzplk
    Jul 19 '14 at 3:02
  • \$\begingroup\$ You may want to look at the book, The Lazy Dungeon Master, by Sky Flourish. It really has all the answers you are looking for. google.com/… \$\endgroup\$
    – Flotolk
    May 11 '15 at 17:54

How much prep is too much is something that's going to vary from GM to GM. You say you're terrible at it, but there are parts of the game you'll find you can get away with improvising.

I don't need maps. They don't add much to my games and it doesn't make a difference if I draw them on the spot or in advance.

But I can't do description. I'll imagine a scene and then forget to tell the players about it, leaving the players to imagine all the rooms as nondescript boxes. I actually force myself to write out bullet points for any area or NPC that should be described.

It's easy to overdo your preparation when you prep everything. When you figure out what elements of your game you can get away with improvising you can save yourself time and work on the parts of game that do need more work.

Furthermore, too much prep can be detrimental to the game. It's easy for a GM to get attached to something he's written. I make this mistake all the time. Once I have an idea I want to see it through and I have a hard time accepting that the PCs may not bump into the idea. On some level I'll push the PCs towards whatever idea that is.

In doing so, I'm also pushing the PCs away from whatever it is they're actually trying to do. With some players that won't matter - they're happy to be rats in a maze. Other characters are more motivated and other players are more willful. A looser game is necessary to give these players space to play out their characters properly.


I ran an open-world game once. It kicked my butt, and I don't think I'd ever want to do it again. That's because I'm the sort of GM who always preps as little as possible, and an open-world campaign naturally forces more prep than a linear campaign. That said, my innate laziness did lead me to come up with some tricks for minimizing my prep time.

All Roads Lead to Rome

Unless you have very specific ideas about what each dungeon in each part of your world is about, you can simply prep one or two dungeons and one or two towns, and use them as whichever dungeon or town your players happen to be headed towards. As long as you always have one town and one dungeon prepped that your PCs haven't seen yet, you can use it to fill whatever gaps you want. This keeps you from feeling like you wasted prep on a part of a world your party never explored, and it makes your party feel as if whichever direction they go, you'll have something ready for them.

Even if you decide that this is a cheap trick, and you want your world to be more set in stone than that, having a dungeon or two in your back pocket is a really good idea for when your party inevitably blunders out of the area you've planned.

Narrow Their Options

Sometimes you can't get away with throwing any ol' pre-prepped dungeon in front of the party. Maybe they're deciding between the Mountains of Doom or the Spider mines, and you want their choice to have obvious consequences. In cases like this, you should always try and have the important choice occur near the end of a session, so that you have a whole week (or month, or whatever your interval is) to prep the path they chose.

If possible, you also want to carefully manage the number of choices available to the party. If worst comes to worst, it's easy enough to prep both the Mountains of Doom and the Spider Mines. But if the party's choosing between the Mountains and the Mines and the Forest and the Bay and the Moon Palace, well, you're not going to be able to prep all that, and even if you do, 80% of your planning is going to be wasted.

How you choose to limit options is up to you. You can do it using terrain and travel times (the Sea blocks your way to the West, it's too far to walk to the south), or by managing what information the party has (they've heard wondrous rumors about the town to the north, an NPC has offered to give them a ride to the town to the east). However you do it, giving your players a clear set of choices will keep your prep time lower and give your players a sense of purpose and direction which will energize your game.

Stay One Step - and Only One Step - Ahead of Them.

As you run your sandbox, you'll begin to get an idea for what motivates the characters in your party. This will allow you to more accurately predict which of your plot hooks they'll bite on, and let you feed them information that is likely to get them moving towards something you've planned. Once you've gotten them to a bit of the world you've planned, you've just bought yourself a whole bunch of time.

While your party is busy crawling through your latest dungeon, or running around your latest town, you have a few sessions to plan for where they might go next. Use your knowledge of the players, and treat their current location as a hub from which they might go to two or three different places. Then plan those places. Repeat as needed, and soon enough your players will have built a large part of your campaign world for you.

What it All Comes Down To

Basically, limit your prep by only planning for things the PCs are likely to see in the next couple sessions. Leave the rest of the world vague. If you run the campaign well, you'll always have a bit of warning before your PCs tumble off the edge of the map.


You can't be prepared for everything. But what you can do, is be reactive to everything. If a wizard, for example, decides enough is enough and casts teleport to simply leave the dungeon - perhaps there is an anchoring effect preventing his travel. If a player decides to go into a room that you didn't have on your map, simply make it empty or an illusion.

Valadil has a valid point. The more time you invest in something, the more personal it becomes. It will also become extremely disappointing if the player characters blow through it in a matter of minutes when it took you a matter of days to prepare it. Set the ground rules, set the locations, set the encounters, and keep resources closeby for improvisations.

Keep notes on your DM screen. Keep the DMG and Monster Manual on your tablet ready to go. Also, you can have something so obviously overpowered behind a door that the characters aren't supposed to open, that they will immediately want to shut it and try another way. Sometimes, the right thing to do is run away.

Also, try to be a facilitator more than an adventure guide. Players that feel "rushed" or "forced" to do something against their will or judgement will probably not have that much fun. Also, setting clear and concise ground rules ahead of time will also limit how many buttons the players can push. Just tell them straight up, "Guys/Gals, I spent a lot of time creating this adventure, and I know we can have some fun with it, but..."

Also, make the reward much greater if they proceed as intended, and much less as good if they deviate from your game setting.


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