How to Get Superpowers?

Hey, Veeky Forums, I've got a super hero campaign coming up, and I'm trying to figure out how to give the city super powers on a citywide scale, similar to the way the hadron collider in The Flash did.

I need some ideas for how to do it.

I'll be bumping with city art.

Mutants. the greatest and laziest power origin ever.

One night everyone in the city has a dream in which a mysterious invisible entity orders them to perform some kind of task as a test. Those who succeed at the task pass his test and when they awaken, they find that they have been given a superpower.

Planet sized organ fragments of an tras-universal space worm that seek out traumatic moments in people’s lives to latch themselves onto people and project abilities in the form of superpowers over the course of a 300 year long science experiment to discover new applications of each organ’s abilities before they destroy our world and move onto the next.

Okay, we're at least original with these.

Isn't that basically the plot to Scientology?

I’ll fucking sue you

Retrovirus goes out of control

Rewriting people’s DNA to give them extraordinary abilities

God and the Devil (or just any good entity and evil entity in the setting) have an argument over the nature of man; whether it tends more towards good or towards evil. To settle the bet, they give superpowers to everyone in a city. Now they're watching how many and which of the citizens decide to become superheroes, and which choose to be supervillians. In the end, only one side will triumph and take control of the city, resolving the bet.

Coordinated not-bang baby gas attack.