Chapter 1 was the first chapter of Fortnite and had a massive story, and over the course of the Chapter, new cosmetics, vehicles and locations were added. Chapter 1 consisted of 10 whole seasons with lots of new things added as well as many things getting removed.
Season 1 was the first iteration of player progression in Battle Royale. It included the introduction of challenges that could be completed for seasonal experience in Patch 1.8 and later, in Patch 1.8.2, the now-closed Season Shop [1]. The season started on September 26, 2017 and ended a few months later on December 13, 2017.
Thematically, Season 2 was focused on heraldic imagery: the cosmetic item set Fort Knights featured 11 items that debuted during this period. Season 2 also saw the first great map expansion in Patch 2.2.0. On January 18, 2018 the map saw the addition of 10 new POIs, including locations like Tilted Towers, Shifty Shafts and Snobby Shores.
Season 3, with the slogan Meteor Strike, was the third season of Fortnite: Battle Royale. It started on February 22nd 2018 and ended on April 30th 2018. The season's theme revolved around space exploration, as well as being the season where the Fortnite storyline began.
Season 4, with the slogan Brace for Impact, was the fourth season of Fortnite: Battle Royale. It started on May 1st 2018 and ended on July 11th 2018. The theme of the season revolved around superheroes. It was also the first season to have a story cinematic trailer and introduce the lore.
Season 5, with the slogan Worlds Collide, was the fifth season of Fortnite: Battle Royale. It started on July 12th 2018. It was scheduled to end on September 24th 2018 but was extended after Epic Games had extended the season to end with the 1 year anniversary of Fortnite being Free to Play. The theme revolved around world collision, following the aftermath of Blast Off, which resulted in things being taken from other realities and put into Reality: Zero.
Season 6 continues the storyline that was started in Season 3. Throughout the second half of Season 5, The Cube rolled around the island, printing seven glyphs before rolling into Loot Lake, sinking underneath the Lake and deactivating underneath the central island. The entire surface of the lake was turned purple in the process At the start of Season 6, The cube activated. It absorbed all of its energy dispersed along the surface of the lake and tore the central island from the ground and lifted it up into the air, with The Cube attached to the bottom of the floating island. The entire island was kept suspended in the air by an an air vortex powered by the cube itself. Loot Lake was renamed to Leaky Lake on account of the mess that The Cube left behind. The central chunk of the lake was completely missing, and in the very center of the ruined lake was a large whirlpool with a bright light coming from underneath it. This likely lead to The Vault, and the location of the whirlpool corresponded to the exact location from where the cube emerged from at the start of the season, likely meaning that The Cube actually entered the vault, but returned back to the island for an unknown reason. The glyphs located around the island became corruption zones. It seems like the cube printed the glyphs to act as energy converters, using up the soil and natural resources in the vicinity of the glyph to convert into energy usable by the cube. In the process, the glyphs corrupted the areas surrounding them, with dead trees and barren soil, along with Shadow Stones and purple vents littering the corruption zones. Only one rift remained at the start of Season 6, kept maintained and controlled in a laboratory within an underground bunker in Wailing Woods.
Season 7, with the slogan You Better Watch Out, was the seventh season of Fortnite: Battle Royale. It started on December 6th 2018 and ended on February 28th 2019. It was originally supposed to end on February 14th 2019, but was extended for 2 weeks following Epic Games' holiday break. The theme of the season revolved around winter and Christmas. Battle Pass owners were also given early access to Fortnite: Creative, in the start of the season. The game mode would become available for everyone 1 week after the start of the season (December 13 2018).
Season 8, with the slogan X Marks the Spot, was the eighth season of Fortnite: Battle Royale. It started on February 28th 2019, and ended on May 8th 2019. Season 8 was the first season that could have been purchased for free if you completed all the challenges during the Share The Love Event. The theme revolved around pirates and adventure..
Season 9, with the slogan The Future Is Yours, was the ninth season of Fortnite: Battle Royale. It started on May 9th 2019, and ended on July 31st 2019. The theme revolved around the future and reconstruction of various locations that were destroyed by the volcano during The Unvaulting.
Season X, with the slogan Out of Time, was the tenth season of Fortnite: Battle Royale. It started on August 1st 2019, and was scheduled to end on October 6th 2019 but ended on October 13th 2019 after The End Live Event concluded. The theme of the season revolved around time, and was the final season of Chapter 1.