Emulating a Variable Ratio Schedule In Trekking the World

Emulating a Variable Ratio Schedule In Trekking the World

Nick Bentley Nick Bentley

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Welcome to this week's behind-the-scenes post.
Today's is about a design principle we’re applying to make our new version of Trekking the World. I’ll start with the principle and then discuss how we’re applying it. Here it is:

The players' experience should emulate the feeling of a Variable Ratio Schedule.

What's a Variable Ratio Schedule, and why emulate one? Why not implement a real one? Here goes:
I used to be a neurobiologist. For at least 150 years, cognitive scientists have trained animals to do tasks. To do a task, an animal needs to be motivated. You motivate an animal by giving it rewards.
I used to train these cuties:
There are lots of ways to motivate animals with rewards, and neuroscientists have experimented with all of them. 
For example, the most obvious one to try: every time an animal does what you want it to do, you give it the same reward. Consistency should make learning easier, right?
Turns out no. Over time, one reward-system has emerged as the most motivational (for every mammal, including humans), and it’s the opposite of consistent:

The Variable Ratio Schedule

In a Variable Ratio Schedule, you don’t reward an animal the same every time it does what you want it to do. Instead, sometimes you might give it no reward, or a small reward, and then once in a while, you give it a big one. 
Systems that create this pattern tend to feel compelling and addictive, and therefore motivating. For this reason, Variable Ratio Schedules have infiltrated our lives. 
For example, every social media platform hooks you with them. Here are impressions for a bunch of Tweets, for example, sorted by magnitude:
When you tweet, you’re rewarded with engagement, but the size of that engagement varies unpredictably from tweet to tweet. 
It’s the same dynamic that keeps people glued to slot machines. 

Isn’t that too random for a strategy game?

Yes! The aforementioned slot machines and apps try to addict you with random rewards. Not only is that unethical (imo), it's also not what strategy games are about. Strategy games are systems for rewarding decisions, not doling out random rewards.
For this reason, we don't wish to put an actual variable ratio schedule into a game. Instead, we emulate the reward pattern, but instead of making it random, we tie the pattern to player decisions:
It’s possible to build games where the reward patterns vary unpredictably across turns as in a Variable Ratio Schedule, but emerge completely from player choices, rather than chance.
Take, for example, the mother of all strategy games, Go:
Go, one of the deepest games ever created, has no luck at all. But! In the game, you can capture your opponents' pieces, and the number of pieces you can capture in a single turn varies unpredictably across turns and games as in a Variable Ratio Schedule:
  • On most turns you don’t capture anything.
  • Sometimes you capture a small number of pieces.
  • On rare occasions you capture a whole bunch.
The games we make at Underdog aren’t nearly so serious or strategic, but the above illustrates a game can emulate variable rewards without luck.

How we’re emulating a Variable Ratio Schedule in our new version of Trekking the World

As you may have seen, we're making a new version of Trekking the World which is a big departure from the original.
One of our goals is to build stronger Variable Ratio Emulation into the game. 
Without going into details, here’s how we’re doing it:
  • In Trekking the World, you’re going on vacation all over the world. On each turn, you choose an Itinerary which determines what you do on the current leg of your journey.
  • Depending on your choices, there are two kinds of resources you can accumulate (among others): Itinerary Tokens, and Encounter Powers.
  • Itinerary Tokens allow you to enhance and extend future itineraries, and Encounter Powers give you special one-time powers that you can use in addition to your itineraries.
  • You can spend as many Itinerary Tokens and Encounter Powers as you want on a single turn.
That last bullet point is key. You can save these resources up and spend them together, and sometimes, when you do, they create major effects greater than the sum of their parts. This creates the feeling of “pulling off a huge turn”, and thus replicates the “big moments” in a Variable Ratio Schedule.
As an example, here are two encounter powers that enhance one another:
This won’t make much sense without understanding the rest of the rules, but the upshot is that the card on the left can multiply the effect of the card on the right to create a major windfall. 
The key to emulating a Variable Ratio Here is to create a situation where the bigger a windfall is, the rarer it is and the harder it is to achieve. We've tried to configure the math of the game so that's the case overall for the new version of Trekking the World. 
Don't hesitate to share your opinions in a reply, positive or negative. I read all your replies (and reply when time permits) and it helps me understand what we're doing right and wrong.
Nick Bentley,
President, Underdog Games Studio
P.S. we're doing a pre-Kickstarter campaign promotion for the game, allowing you to get a full expansion for $1. See and claim the offer here

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