Physics Engine is a simple SceneKit application that simulates gravity and momentum. Physics is not my strong suit, but I ended up making this fun little project a while ago. If you ever build and run this game, you might spend hours staring at a screen of chaotic planets orbiting and colliding.
You can download the latest version of the application with the .dmg file extension here. To install, open the .dmg file and drag Physics Engine into your Applications folder. To launch the app for the first time, right-click it and click Open.
Download this repository, build the project in Xcode, and enjoy!
Easier instructions will be available once Apple gives in to the idea of a third-party app store on iOS.
The gameplay is very simple. You'll be surrounded by planets with different sizes and masses. The mass of these objects double after you click on one of them. Clicking once or twice might not make a difference, but once you've clicked enough, the planets around it will begin to orbit and collide into the planet centered on the screen. For aesthetics, I've added trails and collision particles to make the game more entertaining to watch.
Physics Engine is available under the AGPL license. See the LICENSE file for more info.