Those of you who didn't get a kit but did get a HAT on it's own may not have seen this demo because you didn't get a pre-installed SD card.
It's really good for getting to grips with what IMU sensor is for.
It basically loads up a low poly 3D model of this 1970s spacecraft (ask your grandparents if they remember watching this thing launch):
You can then make it move (pitch, roll and yaw) by moving the Astro Pi in your hand, the input is coming from the IMU sensor.
Go here to download and run it:
https://github.com/astro-pi/apollo-soyu ... /README.md