Ace Combat: Assault Horizon is a spin-off installment of the Ace Combat flight simulation video game series. It was developed by Project Aces and published by Namco Bandai Games for the PlayStation 3 and XBOX 360 platforms in October 2011. The game was later released on Microsoft Windows in January 2013 through Steam and Games for Windows – Live, with the latter notably being the final retail release for the platform shortly before its discontinuation.
The major new gameplay feature is a system called "Dogfighting mode" (DFM), which aims to increase the intensity and bring the action closer to the player. The game features two modes of control, named "Optimum", which prevents the player from doing full rolls, and "Original", which gives the players full control of the aircraft. Co-operative missions and free-for-all Deathmatch have returned, but two new modes named "Capital Conquest" and "Domination" were added to the game. This is also the first Ace Combat title with a plot mostly written by non-Japanese writers, with noted author Jim DeFelice at the helm. Set in 2015–2016, the game's story mainly focuses on members of the United Nations' 108th Task Force, a joint NATO-Russia military organization primarily assigned to quell a rebellion spreading over East Africa.