Horizon is a king of the hill map inspired by popular maps such as viaduct and highpass, set deep in the heart of the badlands region. RED and BLU fight over a disused coal mining plant in order to hide the secret operations going on deep inside their respective underground facilities.
Horizon is a custom king of the hill map for Team Fortress 2. It was developed through many iterations starting in November 2016 and reaching the release candidate phase in July 2017, which meant that it could be considered as a candidate for inclusion within the official game.
The design of the map was based on existing maps, where the layout is broken into 3 distinct sections on each side. Originally the setting of the map was a town in Italy, however quite late in development this pivoted to a mining outpost. During both the alpha and beta phases of development play-testing with was carried out with groups of players to assess how to map played in order to make adjustments accordingly.
For a more comprehensive breakdown of the development of the map, see the development time-lapse