Hello,
I'm not sure if this is the right place to ask, but can anyone here suggest some good gravity simulation software?
Ideally, I'd like to be able to model everything from a simple solar system to an entire galaxy, but I understand the number of calculations involved with galaxy simulations are... well, astronomical. Nevertheless, I want to do this for known systems (with a high degree of accuracy) as well as hypothetical ones.
Open source would be great, as that would allow me to tinker, but I'll take what I can get.

It doesn't have to be pretty, or fast, so long as it's functional and accurate.
Any help is greatly appreciated.