Executable binary file: https://drive.google.com/file/d/0B5gouqMijhbmdFppOTdxM0FER28/view?usp=sharing
Newtonian gravitational force applied on each particles pair.
I used 2d metaball to represent each particles (with multi-pass glsl shader) + 8x msaa.
It was tested on AMD radeon HD6770.
