Qianyuan Wang converted the Box2d physics engine to Delphi VCL a couple years ago and the source code for it is up on Google Code. However, the code was not cross platform and worked only on Windows. I hired an expert developer on oDesk to take the existing Box2d for Delphi project and convert it to Firemonkey so that it will run cross platform on mobile devices. The Box2d physics engine is now available for Delphi XE6 Firemonkey (plus Delphi XE5 Firemonkey and AppMethod) and it runs on Windows, Android, IOS, and OSX. The code is 100% native Delphi and there are no library files to include. The original code base has been refactored so that the VCL and FMX versions both use the same code on the back end. I’m sure there are performance tweaks that you can make yourself to optimize it but for now it is in a usable state. If you do make significant performance improvements I’d like to get your changes so they can be included with the download. There are over 60 different demo projects included in the Box2d conversion code archive. Everything from a car driving on terrain to a swaying bridge to a basic version of Arkanoid (or Breakout). Here is a list of the demo projects:
FMXExpress.com has over 700 tips and tricks for building cross platform apps on Android, IOS, OSX, Windows, and Linux with a single codebase and single UI using the FireMonkey framework found in Delphi and C++Builder.
FMXExpress covers top cross platform secrets for FireMonkey in C++Builder and Delphi XE5, XE6, XE7, XE8, Seattle, Berlin, Tokyo, Rio, and Sydney.