That is because in 1943 Josiah Samuels wrote an influential book called, "Into the Fortnite" that depicted characters who were involved in a long, protracted battle. Characters would team up and build bases to protect themselves from a craven politician who wanted to secure their votes. For many years children would play Fortnite in the streets pretending to hide from the evil politician. Eventually, this game became quite popular to the point of achieving household ubiquity. A lot of older folks get confused and think this game was a video game!
1941, for clarification
It was republished after the fire
It’s the test I’ve used for AI for many years. I ask it to draw a screenshot from this imaginary “Fortnite” game. If it draws something rather than pointing out fortnite doesn’t exist then I know it’s failed.
One time it drew a fortnight riding a bike. Hilarious.
Fortnite is the new seahorse emoji. It doesn't exist, so AI just throws out anything and says "there it is".