Fortnite is an online video game developed by Epic Games and released in 2017. It is available in three distinct game mode versions that otherwise share the same general gameplay and game engine: Fortnite Battle Royale, a free-to-play battle royale game in which up to 100 players fight to be the last person standing; Fortnite: Save the World, a cooperative hybrid tower defense-shooter and survival game in which up to four players fight off zombie-like creatures and defend objects with traps and fortifications they can build; and Fortnite Creative, in which players are given complete freedom to create worlds and battle arenas.

Save the World and Battle Royale were released in 2017 as early access titles, while Creative was released on December 6, 2018. While the Save the World and Creative versions have been successful for Epic Games, Fortnite Battle Royale in particular became an overwhelming success and a cultural phenomenon, drawing more than 125 million players in less than a year, earning hundreds of millions of dollars per month. Fortnite as a whole generated $9 billion in gross revenue up until December 2019.

Save the World is available only for Windows, macOS,[b] PlayStation 4, and Xbox One, while Battle Royale and Creative were released for all those platforms, and also for Nintendo Switch, iOS, and Android devices. The game also launched with the release of the ninth-generation PlayStation 5 and Xbox Series X/S consoles.

Fortnite began from an internal game jam at Epic Games following the publishing of Gears of War 3 around 2011. Though it was not initially one of the developed titles during the jam, the concept of merging the construction game genre, representing games like Minecraft and Terraria, and shooter games arose, leading to the foundation of Fortnite. Development of Fortnite slowed due to several issues, including switching from the Unreal Engine 3 to Unreal Engine 4, a deeper role-playing game approach to extend the life of the game, and a switch of art style from a dark theme to a more cartoonish style. Further, Epic was looking to get into the games as a service model, and brought in Chinese publisher Tencent to help; Tencent took a large stake in Epic as part of this, leading to the departure of several executives, including Cliff Bleszinski, who had been a key part of Fortnite's development. Fortnite's approach was changed to be Epic's testbed for games as a service, and further slowed the development.

Epic was able to prepare to release Fortnite as a paid early access title in July 2017, with plans to release it as free-to-play sometime in 2019 while gaining feedback from players to improve the game. With the release of Fortnite Battle Royale, the player-versus-environment mode was distinguished as "Save the World". Ultimately, Epic opted to release Save the World as a premium title, bringing it out of early access on June 29, 2020