Old School Police: How to Run an OSR Crimecrawl
The sky above the city was the colour of syrup, poured from a bronze ladle. In the golden afternoon light, with a squint, you could have mistaken the foam curdling in the Berrytown alleyway for custard.
That is - if there wasn’t a half-dissolved licorice body lying in the middle of it. Toothpaste, and lots of it, white cream eating into the deep red and black skin of the corpse.
Somebody had gone to a lot of effort to make sure this guy was scrubbed.
Everybody loves a murder mystery. It's a classic plot structure for a reason. And there's dozens of great RPG adventures built around it. Entire systems like Gumshoe built to support it.
But it's hardly a structure that rewards the "tactical infinity" style of OSR play. It's fundamentally linear - you progress towards solving the mystery by finding clue after clue; the inevitable red herring is merely a minor detour. Compare that with a (well-designed) dungeon in the OSR tradition - a non-linear space where the PCs can experiment with different approaches and where the environment responds to their actions.
What if I told you there was a way to combine the two?
This approach is designed to be bolted on to whatever ruleset you prefer: maybe something based on Cairn, Into the Odd, or Mothership - but it could even work with OD&D with a few tweaks.
The Crimecrawl
Start with a single murder. Somebody important, or at least somebody who's important to someone. Sprinkle a handful of clues around the body. But don't stop there.
If you've seen a detective show, you've seen one of these:
The classic cork case board - filled with photos of crimes, suspects, evidence, locations; all connected by pins and red string - looks an awful lot like a dungeon map, if you squint at it the right way. This is going to be your campaign map.
You can prep your crimecrawl caseboard like you prep a dungeon. The starting murder is just the doorway into it. Like a classic Raymond Chandler novel, your PC detectives are going to find out that the rot goes a lot further than one corpse.
And you can run it like a dungeon, too.
Prep: Building the Caseboard
I said above you could start with a single murder. I lied.
You start prepping your caseboard by imagining some grand injustice, corruption, conspiracy, or malfeasance that is already affecting the entire city, district, or region you propose to run your crimecrawl in. Perhaps a local candy baron is poisoning the soda streams in Berrytown with sugarfree stevia. Perhaps the mayor is working to plow Berrytown under and replace it with a brand new gingerbread village. This is the starting point for building your caseboard map out as a GM.
Write down the name or names of the big bosses behind this particular criminal conspiracy. These are your top dogs. Pin them on your caseboard, outlined in red.
Then, you start to populate the criminal network. Start coming up with lieutenants, contractors, errand-boys - at least two tiers of suspects between the bottom and the top dogs. Detail them. Give them strengths, weaknesses, personalities and importantly motivations. Pin them to your caseboard as well.
Write up three crimes that the conspiracy has committed before the start of the game, and gotten away with. Come up with possible clues that could link network members to those crimes.
Finally, imagine someone who would cause a problem for the top dogs. This is your murder victim. They were killed by someone on the bottom tier of your criminal network. Imagine the crime scene, and imagine three clues that link the victim to their murderer - and then three clues that link the victim to the three other crimes.
Here's a caseboard checklist full of suspect types you should include:
- Someone who'll talk and give your players the lay of the land.
- Someone who'll run because a chase scene is a classic part of any great crime drama.
- Someone who'll fight because it's okay to pull damage dice out once in a while.
- Someone dangerous for reasons other than violence; perhaps thanks to their wealth or links to the authorities.
- Someone sympathetic who committed a crime but for motives the players are going to find sympathetic.
- A red herring or someone who looks guilty as sin, but isn't actually connected to the grand conspiracy.
Procedures: The Operation Turn & The Heat Dice
When you're running the game as the GM, you impose order through the use of the Operation Turn.
Each Operation Turn is an abstract period - enough time for your players to take a major action in their investigation. Perhaps they forensically search a crime scene. Perhaps they stake out a candycane warehouse, or raid a local gang hideout. Most actions should leads towards new information and new choices - giving them multiple avenues to pursue, and multiple choices in how to pursue them.
The key in running the game turn-by-turn is to give your players information that opens up choices: what leads to pursue, what evidence they want to secure, whether they want to take an aggressive approach or a stealthy one. Let them navigate the crimecrawl the way they want to.
At the end of each Operation Turn, roll the Heat Dice (a d6). This is the Overloaded Encounter Dice for your urban crimecrawl. If they caused serious damage, noise, or blowback with their last Operation Turn, roll twice and take the highest. Interpret the results as follows:
- Clue: The PCs stumble upon a new piece of information.
- Event: An event outside of the conspiracy changes the city.
- Burnout: The PCs lose access to a resource or ally.
- Crime: The PCs stumble upon/are called to a crime in progress being committed by a member of the criminal conspiracy.
- Conspiracy: The conspiracy takes a major step forward in advancing its interests across the city.
- Attack: The PCs are directly attacked by agents or allies of the conspiracy.
Procedures: Arresting, Prosecuting, Imprisoning
If the PC are police, watchmen, or agents of the law in some form, once they've collected sufficient evidence or witnesses linking a suspect to a crime, I'd recommend applying a level of abstraction to the legal processes.
Give the players a reasonable target in terms of evidence or witness statements accumulated - I would say one strong piece of evidence for a street-level criminal, and three strong pieces of evidence for a well-connected criminal boss. Once they've collected that evidence, they can acquire a warrant and stage an Operation to arrest the suspect - potentially risking violence. But once they're arrested - and the evidence is collected - you can abstract away the court process, and assume that the evidence is sufficient to imprison them.
Alternatively, they can use the threat of arrest to try and flip the suspect and have them turn against other members of the conspiracy. When considering a flip, always ask the following questions:
- What are they offering?
- What does the suspect stand to lose?
- What would the network do if they flipped?
Inspiration
This approach was heavily inspired by the Flame Without Shadow supplement for Blades in the Dark.