Alright, so I created a simple gravity simulation. By simple, I mean it has a good amount of features, but is not very user-friendly. (I am an introverted programmer, what do you expect!) So here is the link to the new download: http://www.mediafire.com/?xyyw1zyvblw (requires 10.5) Features: - add planets - change velocities of planets - zoom in/ zoom out - move planets, change color - draws paths of each planet - graph (can change values of x & y axis) - uses the Dormand-Prince tableau for an accurate simulation (Runge-Kutta) - others - ** new ** zoom with scroll bar Known Issues: - ** Fixed **If you add a planet after the simulation started, there is a chance it will crash (this will be fixed momentarily) - No help file - Graph does not show values (will be fixed by next week) - ** Fixed **After pausing, the velocity arrows show up again in the wrong position (will be fixed soon, possibly by tomorrow) - Simulation is slow if you are drawing lines for a while Files in the download package: - Gravita.app - Solar Systems (Folder) Each "Solar System" is a file that I pre-created. These show off the accuracies, inaccuracies, and abilities of Gravita. (My personal favorite is systemsOrbit.solar) I am hoping that fellow developers in this community will have advice, comments, and questions. If you want some source code, you can ask me, but the code is messy and uncommented, (Sorry about my unhealthy coding habits), but somewhat follows MVC and KVC. All the icons were made by myself except for the saturn file icon, which I will replace. I know that it is unpolished, so questions and comments about my beta are very much appreciated.