Quantum Fluctuations by Markos Kay is a generative abstract animation created through a simulation of quantum physical interactions when protons collide. It's an intricate visualization of interactions that are usually observed through very indirect means.
I love how the work is clearly digital, comfortable with allowing the viewer to see digital artifacts, but at the same time, the actions going on are so complex and dynamic that the underlying logic seems very real and tangible.
I'm guessing Kay achieves the piece by tying various types of animations to different events in the particle simulation, and then movement of the particles shapes those animations. He clearly cares a lot about the physical phenomena underlying the visual experience, so the generative algorithm is probably determined heavily by the particle simulation.
Kay creates effective complexity by devising extremely diverse animations to occur at different particle events, then the randomness of the simulation acting on the order of the chosen animations creates the complexity.