https://www.gamespot.com/articles/halloween-2017-all-the-in-game-events-and-updates-/1100-6453986/

One thing you can count on every October, aside from a bunch of big game releases, are developers releasing Halloween-themed updates and events. Halloween is still weeks away, and already we've seen a number of such announcements, and some of these events are already underway. [Updated October 27 with GTA 5, Absolver, Trove, World of Warships, The Escapists 2, Rift, and many more.]