What’s in it
physics gravity wells pull at 400 px/s², elastic collisions with restitution 0.9,
mass ∝ r², time step capped at 1/30 s
controls click-drag to place, drag wells to move, time scale 0.1× to 10×
renderer OpenGL 3.2 core via SDL2, own GLSL shaders, additive blending, 60-point trails