I think you know how to start the clock, and to turn off ticking and chiming/striking. The new feature is that you can now wind the clock, so if the clock stops working even when the project is going (i.e. the green flag is on), you click on the keyholes to wind them up.
Inspired by Napoleon. IKEA Kupong is here: https://scratch.mit.edu/projects/1157616447/
