Very interesting web sites. Nice simulations!
The unrestricted simulations done by my program are interactive. You can edit the values of the initial conditions of the bodies and observe their amended trajectories.
It is the actual solution. The program in the last chapter of my e-book calculates the trajectories of all bodies, which can be then displayed. To understand how the program works in detail, you need to know something about Java language.
All simulations at my website calculate the...
You can download my new e-book 'N Bodies - No Problem' at:
http://www.grevytpress.com/model.html
You can also try there n-body simulations (all done by the same program).
Speaking about gravity, check an unrestricted three-body interactive gravitational model at:
http://grevytpress.com/model.html
You can enter any values of masses and initial conditions for the three bodies and simulate their orbits.