In three months, the universe will implode.
An ultrastar will collide with a black hole, causing gravitational tidal waves to pour out from the center of the impact and ripple through every nearby galaxy. This will cause a chain reaction of gravity implosions, eventually swallowing up everything we know (and have yet to discover). The only way to prevent it is to realign the planetary systems around the ultrastar so that their gravity fields lock in and contain the implosion.
We know all of this because scientists from the future have brought us the only tool that can save us all: the Gravity Grid. It seems like a simple app on your Android device, but it's actually a highly complex nano-dimensional wormhole manipulator.
To stop the universe from imploding, use this app to solve the gravity grid puzzles in each of the one hundred planetary systems surrounding the ultrastar.
Solve the puzzles, save the universe!