Professor Xavier's son Legion (David Haller) went back in time planning on killing the mutant known as Magneto to prove to his father that he really loved him and to protect everyone from the madness that would become of Magneto. X-men had atepmted to stop him but did not. Legion had confronted both his father and Magneto. Readily Legion prepared a psychic knife that would kill Magneto, he lunged towards him but to his surprise Xavier was not willing to let Magneto die. Xavier lunged between his son legion and Magneto, dying in the process. At that moment it changed the course of time and space from what Altering Reality.
In the new reality, new world, Apocolypse is the ruler of America. New York City Is now Apocolypse Island, and all humans are sentenced to slavery! Only the most powerful mutants being Nemesis Apocolypse's son (Holocaust), Abyss, Sinister, Cylops and the Dark Beast survive to reign alongside the High Lord En Sabah Nur also known as Apocolypse!
In this different nand new world the X-men were founded by Erik Magnus Lehnsherr, better known as Magneto with Rogue by his side rather than the original but dead founder Professor Xavier. The X-men roster has changed slightly and their quest for peace remains unchanged. due to the drive instilled in Magneto by a man he once called a dear friend-the late Charles Xavier. The X-men is consisted of Magneto, Rogue, Sabertoothand his link Wildchild, Blink, Colossus, Morph, Quicksilver, Weapon X, Jean Grey, Storm, Nightcrawler, Iceman, Scarletwitch, Shadowcat, Sunfire and later Gambit who later left the team.
As for the former members such as Gambit, Beast and Cyclops, they all went there own ways. Wolverine now known as Weapon X as well went his own way fighting in the mutant rebellion against the tyranny of Apocolypse. Named after the governement program that trained him, he is a living weapon possesing a fast mutant healing factor, extraordinary keen senses and an unbreakable adamantium skeleton and claws as you already know. Weapon X lost his left hand to the forces of Apocolypse, Wolverine costantly struggled to keep him from unleashing his animal nature in his defiant battles to preserve humanity. He is also helped by his wife Jean Grey former wife of Scott Summers better known as Cyclops.
Gambit in the alternate reality is not an X-man. Instead he leads a band of thieves calling themselves the X-Ternals, stealing from the now ruling class, giving to poor humans and weaker mutants. Although many things are different in the new world, one thing remains the same, Gambit's love for his chere, Rogue. When Magneto had won Rogue's heart Gambit had left the team.