This project is just a spaceship falling in some low-gravity environment. You you control it with your arrow keys, Up to fire your rocket, and Left-Right to rotate. I've added a bunch of comments to help walk you through what each block is doing. So after clicking "See inside," start with the comment that begins "START READING HERE." Hint, it's in the top left of the Rocket sprite's code.
You can see a variation of this rocket used in the game Lunar Lander here: https://scratch.mit.edu/projects/366483283/