Just for fun, I set it up with six bodies, each 1 unit mass and at 1 unit from origin, but along the three different axes (an octahedron). No initial velocities. Start the sim, they fall towards the center, and then BLAMMO they rocket off in opposite directions at high velocity. Clearly, no conservation of energy here (at least when the bodies are arbitrarily close to each other).

Simple pleasures.

I doubt they implemented any collision physics.