BROKEN UNTIL I GET AROUND TO FIXING IT USE TURBOWARP OR SUFFER! https://turbowarp.org/413885324?turbo The blue points start on the edge of the screen and randomly walk around until they touch a red point, when this happens, they stick there and become a red point.
Based on The Coding Train's Coding Challenge #34. 1/21/22: I could probably make this faster by using a KD tree to speed up the search for nearby circles. Or maybe a spatial hash.