While the plot of most shooter games doesn't evolve much beyond "grab gun, shoot", Overwatch has a surprisingly rich backstory. The Overwatch plot begins with the Omnic Crisis, when sentient robots rose up. In the game's universe, Earth made huge advancements in technology, medicine, and robotics but in 2046, the Omnics went rogue and started building an evil army.
The United Nations created an international task force called Overwatch to respond to the rogue army of sentient robots. They gathered soldiers, scientists, and engineers from around the world to fight the Omnic threat. Eventually, Overwatch overcame the Omnic Crisis and continued to maintain order and peace for 20 years. Its members became globally celebrated heroes... for a time.
But after years of allegations of corruption and a series of failed missions, the UN launched an investigation in Overwatch which led to the Petras Act, declaring that any actions done in the name of Overwatch would be considered a crime. Fast-forward to 2076, and Winston, a genetically engineered gorilla, rebuilds the Overwatch Communications Network and sends out a call "to the former agents of Overwatch" summoning a rag tag gang of former Overwatch heroes.
And that's just the beginning. Here are the Overwatch backstories you need to know.
After losing command of Overwatch to Morrison, Reyes parts ways with the team and takes up with Blackreach, a covert ops division of Overwatch. When Reyes mysteriously disappears after his falling-out with Morrison at the Overwatch Swiss HQ, the undead Reaper appears. It turns out Reaper works for Talon, a known terrorist organization, and hunts Overwatch members.
Torbjorn is another Overwatch OG, dating back to the original strike team. He joined Overwatch as a means of repenting - before the Omnic Crisis, Torbjorn worked as a freelance Omnic engineer for companies like Ironclad Guild. But, eventually, the machines he helped create turned on humanity.
Torbjorn joined Overwatch as their lead engineer and created tons of amazing gear for the team, like Reinhardt's crusader armor. After Overwatch disbanded, he continued working to right his wrongs by preventing his machines from being used for evil.
Widowmaker's real name is Amelie Lacroix, wife of Gerard Lacroix. Gerard led an attack against the terrorist organization Talon and they hunted him in retaliation. Unable to assassinate Gerard, the organization kidnapped Amelie and reprogrammed her to kill her husband. She continues to work for Talon, assassinating high profile targets.
No, seriously. Genji is the youngest son of the leader of the criminal Shimada ninja clan in Hanamura. After parting ways with his family, the clan made an assassination attempt on him. Overwatch brought him back to life as an Omnic cyborg. Genji struggled with his Omnic half at first, but eventually found peace with the help of his mentor, Zenyatta.