Fortnite was originally released as a Battle Royale in July, 21 2017 in order to capitalize on the battle royale genre which was blowing up in popularity at the time. Fortnite was released at a time when Pub G was the leading game in the battle royale genre. But unlike Pub G, Fortnite was completely free to play which allowed it to pass Pub G in popularity and never have to look back.
Fortnite was also completly original as opposed to other battle royale games because of one simple but game changing mechanic. That mechanic being building which adds an completely different aspect to it. There are three different building materials.