Move the mouse and Scratch Cat will try to swing over to it. Press 'P' to toggle the pen. Press 'C' to clear all pen trails. If you turn on turbo mode and use the pen, you can generate some really cool patterns!
Inspired by @Paddle2see 's project here: https://scratch.mit.edu/projects/166794/ If you're wondering where the inspiration came from, I wanted to try and recreate the yo-yo effect. It's not very accurate but it is quite close.