Use the speed control to change the speed of the stars. The stars will follow the mouse pointer.
I made this some time ago and did not publish it, so why not do it now. I don't do any Scratch these days but I found this again recently so I published it. I based the code off an old archival site which gave pseudocode for generating 3D starfields. I don't remember what it was, but you should be able to find it with enough searching. I just modified it to follow the mouse pointer. The particles are really fine so you may have to do full screen to see them properly.
