Storyline is a game about guessing trends. You chart progress of a trend over time (e.g. growth in # of internet users from 1975-2010), and later compare your guess with reality.
For example, here's my guess for how internet adoption grew in the US, compared with the actual trend:
I underestimated how slow adoption was until 1990, and how rapid it was after that.
Here's another one of murders in New York City, I was completely wrong:
Alex Tabarrok also posted a quiz today which turned out to be incredibly difficult. E.g., I'd always assumed heart disease deaths probably looked like this:
I expected deaths to be relatively flat until our food habits changed and more deep fried food, high fructose corn syrup, and other highly processed foods became popular. Then a drop in the 2000s as people became more health conscious.
Instead reality looks like this:
Why did heart disease deaths do down in the 1970s despite diets probably getting worse? Apparently it's because statins were discovered around that time which help reduce blood cholesterol levels.
If I learnt anything from Storyline, it's that the world is ridiculously complex and I don't understand it very well.