Hey mate, sorry for late reply,was on weekend. And glad that you like it.
As for overdraws, that was just combine of rules which i tried to follow.
In general, always keep in mind limits per frame and don’t get over it.
Making density by texture fill instead of increase particle quantity.
Place all the emitters in different places, to avoid overdraw even from the start.
And always play with timings as while turning on one, don’t forget to off another)