UPDATE 29/10/19: Fortnite’s Halloween-themed event, better known as Fortnitemares, is now underway on all platforms, introducing a range of appropriately spooky new limited-time modes, challenges, and rewards, as outlined in developer Epic’s announcement post.
Fortnitemares’ centrepiece this year is arguably the battle against the fearsome Storm King – the big bad of Fortnite’s other mode, Save the World. This particular skirmish unfolds in its own separate limited-time mode and pits squads against the intimidatingly large Storm King and his waves of undead pals. Those that survive get a lovely spooky umbrella for their troubles.
There’s a bit of undead malarky happening in the main battle royale mode too, with Season 2’s brand-new island map changing for the very first time. Now, the centre of the map, dubbed the Isle of Storms, is spewing out evil forces, and will continue to do so until players stem the tide.
Source: Eurogamer Tomorrow's Halloween-themed Fortnitemares event gets official start time