Pledge, Turn, Prestige: A Good Demo is a Magic Trick
In Christopher Nolan's movie "The Prestige", a theory explaining the ingredients to a successful magic trick is stated. There are three steps to this:- the Pledge
- the Turn
- the Prestige
The pledge is when you setup the trick, building the audience's expectations. What is the situation? What are you going to do about it?
The turn is a first trick. It's impressive— but the audience was expecting something to happen anyway. Although in any other circumstance it would be impressive, in this context it is the norm, what they signed up for, so they aren't satisfied just yet.
The prestige is when the magic really happens— it's the conclusion of the trick that just blows the audience away, leaving them wondering what just happened and almost truly believing in magic.
Your demo is a magic trick. If you want your demo to be impactful, you need those three elements.
Here's an example of a great demo by Bret Victor, where he shows a prototype for a game design interface he made. Watch the video, and pay attention to what he says and how the audience reacts.
First of all, he shows off a basic game running with the code right next to it. He then changes the code, and the effects are visible in real time. He explains what's going on, and why one would want to use that. That's the pledge— it's already a pretty good prototype, but nothing ground breaking; code hot swapping has been around for a while, and dynamic languages make this almost trivial to implement. The audience likes it and a good portion of it has probably never seen a game development environment like that, but they signed up to see a demo.
Then comes the turn— Bret Victor shows off a slider that allows him to rewind through time. At this point, you hear murmurs in the audience. This is definitely very cool, and he gets a round of applause. His demo could have ended here, and it would definitely have been a pretty good demo.
But right away, Victor starts the prestige: "when I change the code, I change his future"— and effectively, as he changes the code, the future of the entities on the screen is changed. The audience is completely won over at this point, earning him "oohhhhs" and another round of applause. At this point, he can just say anything he wants, his demo is complete.
Pledge, turn, prestige. If you want a demo that people will talk about, make it a magic trick.
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