Fortnite Season 4 includes some new landscape to play in, new gravity defying Hop Rocks, over 100 new cosmetic items for the Battle Pass, and more. It should also be noted that for the first time, the Battle Pass for Season 4 includes sprays. Those playing the single player based Save the World also have some new content today including some new cosmetics and the Origin Story part (5 quests, 1 Landmark Mission) for a new Blockbuster Event.
There are too many things for us to list here that have been changed, updated, improved, or modified. Be sure to hit up the official Fortnite v4.0 changelog for the full details about your favorite game mode. There's literally something there for everyone.