Here's where things get long. The majority of Tron content we consume in the modern day takes place here, on Kevin Flynn's grid. There are three main story entries here-- the movie, Tron: Legacy, the game, Tron: Evolution, and the television series, Tron: Uprising. The three combine to create a greater story arc. Upon release, the three did not follow chronological order. They will be told in story order here. The three all tell a common backstory--
Kevin Flynn, a short few years after the events of the original Tron, begins creating a grid of his own. He takes with him the code for the Tron program, and creates a new Clu (Codified Likeness Utility), the latter of which's purpose is to "create the perfect system." Time works differently in this computer world he's created, allowing him to spend hours and days in the Grid and come back home as if he had only gone to work for the day. As time goes on, the Grid develops into a blooming society, until the ISOs (Isomorphic programs) show up. They turn everything Flynn thinks he knows onto its head. These ISO programs, unlike the basic programs that Flynn made to populate the Grid, were created by the Grid itself, in something called the Sea of Simulation. Flynn wants to study them, believing they can change everything we know about modern technology and medicine. Clu, though, cannot understand this. He sees the ISOs as imperfect, hindering his "perfect system." Clu and Flynn fight, and it ends with Clu taking over the Grid, banishing Flynn and obliterating as many ISO programs as possible.
Tron Evolution is a video game, released in 2010 right before Tron: Legacy. It follows the player as they take the role of a security program named Anon. It takes place during the emergence of and political unrest around the ISO programs, as a virus named Abraxas tries to corrupt the grid. Abraxas, formerly an ISO himself who was corrupted by Clu and turned into a virus, attempts to obliterate all ISOs on the Grid. Anon gives chase, following Abraxas all around the Grid. Abraxas ends up being derezzed, or destroyed, by Anon, but not before many ISO casualties can occur.
Tron: Evolution is important for its description of the downfall of the ISOs, something that Legacy doesn't touch on despite its large importance to all of the events on Flynn's Grid. A number of familiar faces who show up later on are shown here, such as Quorra, Tron before his repurposing, and some others.
Tron: Uprising was a television series that aired on Disney XD from 2012-2013. It follows a mechanic program named Beck. Under Clu's rule of the Grid, Beck's city is seized and one of his best friends is derezzed right before his eyes. Tron has been missing for some time now, and Beck takes it upon himself to act under Tron's name, using Tron's ideals. It turns out Tron is alive, though hurt, and he takes Beck under his wing and trains him to fight Clu's regime. The show was cancelled prematurely, likely in part due to low viewership, despite its extremely positive reception, even with older fans due to its mature tone.
All things considered, Tron: Uprising doesn't hold a lot of relevance to plot in relation to the other entries of the series, utilizing a large plethora of original characters that do not appear in any other Tron media. Spare Tron, Clu, and occasional appearances of Quorra and Flynn, it's entirely original. Though, in my opinion, this is not a negative thing. I could honestly sing praises for Uprising all day. It has a distinct and appealing art style, its story is well-suited for young and older audiences alike, and the characters, despite being computer programs, feel very human. Its only fault is the rushed ending due to its premature cancellation.
Tron: Legacy is very well-known to my knowledge, the second major film entry in the Tron series releasing in 2010-- an almost 30 year gap between the movies. Perhaps I think it's more popular or well-viewed because it was out when I was a kid, and I heard lots of talk about it for the years following its release-- even watching it not knowing about the original 1982 film for a long while.
Tron: Legacy follows Sam Flynn, son of Kevin Flynn. Time has passed accordingly since the first movie's release, Sam being in his mid-20s. Kevin Flynn went missing some time in 1989, nobody being able to find him, trapped in the Grid. Sam receives a mysterious message from family friend Alan Bradley, saying Flynn paged him for the first time in 20 years. As Sam goes to investigate, he gets taken to the Grid himself. It was actually Clu who lured him there, intending to get Alan, and use his entrance to the Grid as a way to get out to the real world and rule over them too. Sam, with the help of the last ISO, Quorra, and his father, attempts to save the Grid from Clu's tyrannical rule.
Legacy brings the saga of Kevin Flynn's grid to a close. At the end of the movie, Flynn and Clu reintegrate, creating an explosion that assumedly caused a large amount of destruction. Sam and Quorra used the portal to return to the real world, but what truly happened to Flynn's grid is uncertain. Overall, everything built up by Evolution and Uprising is ended here, even with it being up in the air.