About
Ace Combat: Assault Horizon is a 2011 spin-off in the Ace Combat flight series, developed by Project Aces and published by Bandai Namco for PS3 and Xbox 360, with a Windows release in 2013. Open Horizon is an open-source implementation of Ace Combat: Assault Horizon's rendering and physics, with builds for Windows and Linux. It requires resource files from the original game.
How it differs from the original
It is DFM-free, leaving out the original's close-range Dog Fight Mode, and adds a mission editor and support for custom decals.
Getting started
You need resource files from a copy of the original game; downloads are posted on the author's blog and build instructions are on the project wiki.