Press the green flag TWICE, then tap screen. Press the dot in the middle to change its base colour, the smaller dot to the bottom right of it will show the base colour. Adjust the sliders as you wish, or press the “Randomize!” button to randomize them. The switch controls whether or not size determines speed. In other words, if the switch is on, the bigger the particle is, the faster it moves. When you’re happy with your settings, just press “Start”, and enjoy the show.
All 100% by me. If you want to use the code, feel free to, but remember to give credit because this took a lot of thought!