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Mars Crisis: Moves

This post is a continuation from Mars Crisis: The story engine. In this series of three posts, I explain the design of the story engine in Mars Crisis. Mars Crisis is a one man project. It’s based on Twine 2 using the Harlowe 3.2.2 story format. The latest version of the game is available here.

Mars Crisis is a politics game and politics is about influencing people to do what you want so I wanted to make a story engine that spotlights this.

You influence someone with rhetorics using a mix of ethos, pathos, and logos. Ethos is when you appeal to authority, to do what is right. Pathos is when you invoke an emotional response, to do what is best. Logos is when you appeal to reason, to do what is wise.

A recent example that really boils this down to the core is when Joe Biden defended his decision to withdraw from Afghanistan and said:

“I give you my word: With all of my heart, I believe this is the right decision, a wise decision, and the best decision for America.”

Joe Biden, President of the United States

So let’s make this the core in Mars Crisis. Every change of the colony state boils down to Kelly influencing someone to support her idea. Kelly can either explain her idea (logos), tell that someone that it’s the right thing to do (ethos), or sell the idea (pathos). Three choices: Explain, Tell, or Sell.


I realise now that I’m doing an awful lot of explaining here and not a lot of selling or telling. Time for a little intermission:

Play Mars Crisis! It’s great! All your friends love it. Your mother thinks it is the right thing to do! Clean your room and go play Mars Crisis! Play it now!

Mars Crisis is the most innovative game of 2021! Recommended by serious game designers. 5 stars out of 5!

Your favourite review site

Ahem. So. On with the explaining.

Only the fun ones

I’m basing the moves in Mars Crisis on the Apocalypse World engine. Apocalypse World is a tabletop rpg published by Vincent Baker that has influenced a large number of tabletop games since then.

The core of the Apocalypse World engine is that players can have their character do something in the fiction that then triggers a move. A move typically means rolling 2d6 adding a modifier. A result of 6 or lower is a miss, a result of 7-9 is a partial hit, a roll of 10 or higher is a hit.

Failures are serious failures, “no, and…”, not the old boring “nothing happens, try again”. Not only do you fail to convince Ursula, she is also now real mad at you and calls for workers to strike immediately. However, these are cool failures that take the story to new places. Failing is fun! (This is the ‘fail forward’ principle)

Partial hits are success with a substantial cost (“yes, but…”). This is where the resources come into play. Kelly persuades You Yan, but makes a promise she can’t keep (that the police will get on the case immediately).

Hits are genuine, unconditional successes, the kind that makes you feel that Kelly really makes a difference (“yes, and…”).

This leaves out the boring outcomes “yes”, “no”, and “no, but…”. Together with the probabilities, this mechanic produces a certain kind of stories. A typical modifier is +1 or +2 and the typical outcome is a partial hit. Each roll has about a one in six chance or one in four of failing and it’s worthwhile for the player to chase every modifier that can bump the roll to +3 or even +4.

Hit 10+13610152128
Partial hit 7-9712151615127
Miss 6 and lower28211510631
Outcomes by modifers. Number of rolls that produce a given outcome out of the 36 possible combinations of rolling two dice adding them together.

If we want every roll to be able to produce all three outcomes, we need to keep the modifier between -2 and +4.

So at the culmination of every situation, Kelly will choose to influence someone by either explaining, telling, or selling.

She outcome will then be either a Hit, Partial Hit or Miss based on a roll of 2d6 with a modifier between -2 and +4.

Rolling dice and interpreting a result in the editor. For test purposes I’ve introduced a way to set a predefined result.

In Apocalypse World style phrasing the moves then becomes:


When you explain an initiative to someone to win them over, roll+modifier.

On a 10 or higher, you explain your idea and the other understands and agrees to do as you want.

On 7-9, you explain your idea and the other understands and agrees to do as you want, but (pick one):

On a 6 or lower, 


When you tell someone to support an initiative, roll+modifier.

On a 10 or higher, you tell the other to support your idea and the other accepts and agrees to do as you want.

On 7-9, you tell the other to support your idea and the other accepts and agrees to do as you want but (pick one): 

On a 6 or lower, 


When you sell an initiative to someone, roll+modifier.

On a 10 or higher, you sell your idea to the other and the other buys it and does as you want.

On 7-9, you explain your idea and the other understands and agrees to do as you want but (pick one): 

On a 6 or lower, 

Next time

For all three moves, regardless of the outcome, the time advances by one.

Restrictions foster creativity, choices builds agency: I have narrowed down the “cost” option to one of two for each partial hit. In a tabletop version of the engine, the player making the roll will also get to choose the variant of the partial hit. For the digital version, the choice is made in the script to keep things simple.

Next post I will go into the components making up the modifier. These are the secrets that will help you win Mars Crisis!

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