Click the green flag, sit back, enjoy. To change the number of stars, drag the slider, then (re-)click the green flag. It takes up to 10 seconds to reach full star density. Please feel free to remix!
This is neither the first nor the best starfield project in Scratch, but it may well be the one with the smallest and simplest code: only 22 blocks. All code and graphics by @heldlaw, November 19, 2021. Inspired by the starry background in 'Gyruss' (and to a lesser extent by 'Starfield Simulation', a Windows screensaver that appeared many years later). https://en.wikipedia.org/wiki/Gyruss Each clone carries 3 stars. The maximum number of stars is 900 (given that Scratch 3.0 is limited to 300 clones). The 3D effect is achieved by gradually resizing each clone in 99 steps, going from 4% to 85% with hyperbolic growth. BUGS I know: it's not a starfield, it's a tube made of colored balls. Whatever; it looks cool. The clones are evenly distributed ONLY if the number of clones is a multiple of 100. And even then, clones may start clustering when the project has been running for a while.