(v0.9) This is a simplistic solar system model using Newton's laws of gravitation. Controls: Press 'R' to reset. Pan camera by clicking and dragging on the background. Click on an planet to set the camera to focus on it. Zoom in and out with the icons in the lower right corner. Change the time scale with the buttons in the lower left corner. (Warning: higher speeds cause less accurate results) To add or remove a planet, use the yellowish buttons to the left of the zoom icons. Adding a planet: 1. Click on the 'add planet' button. It looks like a yellow ball with a plus sign. 2. The simulation will pause. Move the mouse to where you want to place the planet and click to place. (Note: press space to snap to a 10px grid) 3. A velocity vector will appear, pointing towards the mouse. When you click again, the object will move in that direction with a speed proportional to how long the vector is. (Note: press space to snap to a 10px grid) 4. The simulation will resume, and the new planet will interact with the others. Removing a planet: 1. Click on the 'remove planet' button. It looks like a yellow ball with a red X. 2. The simulation will pause. Click on the planet you want to delete. 3. The simulation will resume, sans planet. Note: For your own safety, and the safety of others, please do not remove the sun. Oh who am I kidding, you're going to do it anyways.
Completely thanks to @9994 , I just made a save level script.